Washington College students Richie Torres, Monica Benitez, Jacob Marberger and Morgen Ricketts pose after participating in events tied to the Relay for Life fundraiser to fight cancer in March 2015. Marberger has been missing since Monday, Nov. 16, and officials closed the school amid uncertainty about his whereabouts and a belief that he is armed. (Courtesy of Morgen Ricketts)

— With one phone call, Washington College went from the usual easy patterns of a small liberal-arts campus in fall — quiet discussions in seminars on the lawns, late nights writing papers, friends paddling on the Chester River — to a place under siege.

Before dawn Monday, the parents of a sophomore called school officials and told them that their son was distraught about things at the college. He had driven home to Pennsylvania in the middle of the night, taken a rifle case and left. They hadn’t been able to reach him since, and they didn’t know where he was headed.

That call — and a police warning that 19-year-old Jacob Marberger was seen Monday morning buying ammunition — propelled this small college on Maryland’s Eastern Shore into a crisis unprecedented in its more than 200-year history. Although no direct threat was made, administrators worried that Marberger, potentially armed and in the throes of a personal meltdown, could be an imminent danger to campus.

Administrators locked down the campus, then evacuated all students, faculty and staff and took the unusual step of shutting down the college until the end of the month.

It was the kind of call every college president dreads at a time when mass shootings — such as the one at an Oregon community college this fall, when a student gunned down nine people — are all too real and anonymous threats are easier than ever to make, and share, on social media.

Jacob Marberger, a student at Washington College, is missing and is believed to have a gun taken from his family home in Pennsylvania. (Courtesy of Washington College)

Those risks and those unknowns — felt recently at Harvard, where a bomb threat evacuated four buildings this week; at the University of Missouri, where racist death threats frightened many last week; and at Eastern Kentucky University, where violent graffiti shut the school down for several days last month — leave college leaders with a painful choice.

“It’s extremely tough,” said William Taylor, president of the International Association of Campus Law Enforcement Administrators, and chief of police at a college in Texas. “Each one is unique.” There are some ways to try to gauge how viable a threat is, but often it’s all but impossible to know for certain.

“It has been a very difficult fall,” he added, with so many threats of violence to the nation’s campuses. “I hope it eases up, but I don’t know. It seems to be getting more and more prevalent.”

There were no perfect options at Washington College, said Sheila Bair, who became its president in August and expected her tenure to be a respite from highly visible positions in the government in times of crisis. (Bair was assistant secretary for financial institutions at the Treasury Department after the 9/11 attacks, which triggered chaos on Wall Street. During the peak of the subprime mortgage collapse, she headed the Federal Deposit Insurance Corp.)

This week, Bair went back into crisis mode. The school issued an alert soon after the call, advising students, faculty and staff to shelter in place. For an entire anxious day and night, the college was on lockdown — and quickly shut down again when they received new information from police the next morning when a warrant was issued for Marberger’s arrest.

On Wednesday, college officials announced that the school would close through the Thanksgiving break, and the lives of 1,400 students were thrown into a different kind of turmoil — packing and worrying about academic deadlines and last-minute flights home.

“I think we’re trying to strike the right balance,” Bair said Thursday. “Until he is found, there will be no certainty.”

The Washington College campus in Chestertown, Md. (MARY F. CALVERT/For The Washington Post)

The college community is worried about him, she said, and hopes he is home soon.

But with so many unknowns, even for someone like Bair with access to confidential information about students, many college officials choose caution. Even if it means stopping their fundamental role of providing an education.

“The guidepost is student safety,” Bair said. “You don’t worry about who is going to criticize you or what your press is going to be like. You focus on students and their safety and that leads to good decision making.”

The choice came after the school received a call, one that Jon Marberger said was not an easy decision “and even more difficult for a parent to do.”

“But we raised our son to do what is right,” Marberger said in an interview Thursday. “And the right thing to do was to alert the college. We never saw Jacob as a threat to anyone at any time. But to not inform the college would have been dangerous.”

He hopes that people will think of the teenager they know, an intellectual, conscientious young man, active in theater, who had loved his fraternity and rose to a leadership position in student government — and “turn the ‘hunt’ into a ‘search.’ ”

Their only child was last seen Monday morning. Police said they have no indication of his whereabouts.

“Terrified,” Jon Marberger said, “is an understatement.”

One of Jacob Marberger’s former teachers in Cheltenham, Pa., outside Philadelphia, organized a candlelight vigil for him Wednesday night at the temple where he had celebrated his bar mitzvah years earlier. People talked about “this sterling individual, academically brilliant, outstanding young man,” said Rabbi Robert Leib of Old York Road Temple-Beth Am.

He’s very smart and funny, some of Jacob Marberger’s friends from college said, an outspoken conservative who wore cargo camouflage pants to class and enjoyed debating about politics, particularly the Second Amendment right to bear arms.

Jacob Marberger also is known for being kind and respectful, his friends said, even to those who do not share his views.

“We know he wouldn’t hurt a fly,” said sophomore Richie Torres, who lives with Marberger in Cecil House, where half of the 24 student residents are also members of the Marberger’s former fraternity, Phi Delta Theta.

Taylor Frey, president of Washington College’s student government, said that Marberger was “extremely passionate” about his role as speaker of the student government and took seriously his role in building consensus and moderating debate.

“He was just outspoken on any issue that came up on the senate floor,” Frey said. “He wanted to make sure we were engaging on all of the issues.”

Marberger’s position in student government was his proudest accomplishment, his father said.

A group of Washington College alumni launched an online fundraiser for him — which was taken down shortly after it debuted — “to let Jacob know that we respect him and are here to help. He is one of us. We hope you will join us in letting him know that he is not alone and that the entire Washington College family wants him safe.”

Bair echoed that concern: “He’s out there by himself. I can only assume he’s feeling isolated. We are worried about him, absolutely.”

Jon Marberger is trying to figure out what went wrong. He believes that the trouble started when his son said he witnessed sexual harassment and, out of a sense of honor, reported another student leader for it.

That created a rift, both within his fraternity and the student government association, he believes.

The school’s director of public safety described one incident in which someone set a trash can full of water outside the door of Marberger’s dorm room so that the carpet got soaked when he opened it. He felt ridiculed, persecuted.

Two days later, in early October, he allegedly brandished an antique pistol at his fraternity while drunk, alarming students. Bair said that Marberger at first denied owning the handgun, which was later found at an off-campus apartment.

“He violated school policy, very strong policy, against guns on campus,” Bair said. “It had to be dealt with. We had no other option but to respond the way we did.”

Marberger was expelled from the fraternity, suspended from school, and he was facing expulsion. The events hit Marberger hard, his friends said.

“He’s had a bunch of bad, unfortunate events, and a lot of things have spiraled out of control,” said Blayney Del Priore, 19, of Garrett Park, Md., one of his close friends. “He’s a very successful kid, so I don’t know that he’s ever dealt with something this low.”

When Marberger went back to campus this month, he was anxious about facing people, his father said, but the last time they spoke, Jacob Marberger was very optimistic, pleased that his professors were so warmly supportive of him.

But something happened between 9 and 11 p.m. Sunday, he believes.

Frey said he last saw Marberger at a meeting to discuss his future role in the student government, adding that “Jacob was an advocate in the student government association for holding folks to a high standard, and I think he understood that he fell under that high standard as well.”

He saw Jacob Marberger later that Sunday night.

“I said: ‘Hey, Jacob, how are you? Everything going all right?’ ” Frey said. “He said something along the lines of, ‘I’m doing all right, but submitting my resignation.’ ”

Frey’s last contact with him was at 1:30 a.m. Monday when he received an e-mail from Marberger resigning as speaker of the senate.

Jon Marberger said his wife woke him up at 3:40 a.m. and told him that she had just heard their son leave the house. He didn’t answer their calls or texts. The last time he was seen, according to police, he was buying ammunition at a store north of his home town.

Some people at Washington College are terrified for their own safety. Some people are terribly worried about Jacob Marberger. Some people are a little of both — uncertain about the risks, uncertain about the reality.

Bair said that if Marberger is not found before Nov. 30, when the school is scheduled to reopen, the campus will have additional security procedures to ensure that students are safe.

“We’ll be very vigilant,” Bair said.

Jennifer Jenkins contributed to this report. Svrluga reported from Washington.