It’s just a three-block walk from the Howard Plaza Tower where Mariah Williams lives to the main Howard University campus. It’s lunchtime. There’s plenty of daylight, plenty of people around.

But Williams and three friends patiently waited on Friday for a shuttle to take them up Georgia Avenue and to class.

Even in the middle of the day, the short walk is not worth the risk, the 21-year-old nursing student said.

Days earlier, a fellow student in Williams’s off-campus residence hall was robbed by two gunmen who broke into his room. It was just one in a series of armed robberies, thefts and assaults on and around the university campus in the past few weeks.

“I understand there’s crime,” Williams said. “We’re in the city. But this was too close. It’s where I live.”

Howard University Police Chief Leroy James said there has been a small spike in crime since September, but most worrisome is that many of the incidents have been more violent than the typical snatch-and-grabs of purses and cellphones.

A student’s car was stolen after men forced a woman out of the driver’s seat in a campus parking lot. A student was robbed at gunpoint at Greene Memorial Stadium. Four students walking home from a party were attacked, and one was hit in the face. Another man was held up by a gunman outside the campus theater.

James attributed the recent rise in crime in part to this weekend’s homecoming festivities, which draw scores of visitors to the urban university. The college prides itself on being an integral part of the historic Shaw neighborhood. Its campus is open and accessible from major city streets.

“Some of the guys who live around here are the criminals, and they know this,” James said about homecoming, adding that the event brings an influx of potential targets with iPhones and other desirable devices.

“We’ve got a lot of guys out here looking for an opportunity.”

Authorities are playing down the reported home invasion that occurred at dawn on Oct. 13 in the west tower at Howard Plaza, saying it doesn’t appear random. But a report of an armed intrusion at a building full of students prompted police to convene a town hall meeting, and the incident has heightened fears.

James said his 85 uniformed and armed officers, along with 20 unarmed security guards, will be on alert this weekend.

Police said overall crime has dropped in and around campus. Since James arrived on campus in 2008, after 27 years on the Prince George’s County force, robberies dropped from 47 to 29 in 2010, 22 in 2011 and 14 so far this year.

“I think we’re trending in the right direction,” James said.

In addition, crime is a fear on college campuses throughout the region. Last week, several students were robbed near the University of Maryland in College Park. Four American University students recently reported being groped on Massachusetts Avenue, and on Oct. 10 a young man was shot a block from the main entrance to Gallaudet University.

Still, Williams and other Howard students say they are unnerved by the steady stream of crime alerts that have landed in e-mail inboxes over the past few weeks.

Campus police said the student robbed at the stadium was surprised by his attacker, who snuck up from behind after using the bleachers for cover. Some attacks, such as the one at the stadium, occurred late at night or in the early morning, targeting students walking home from parties.

Others, though, happened at times when many people are out, and in open areas, such as when the student was forced from her car at 8:30 a.m. Police said the man robbed at gunpoint in late September in front of the Aldridge Theater was there at 6:20 p.m.

Williams said that, just last week, a friend of hers was robbed of her book bag in a parking lot. The robber escaped with a computer on which the victim had her personal information stored.

“She wasn’t hurt,” Williams said. “But the guy basically stole her life.”