A Pennsylvania man was arrested early Wednesday at the Trump International Hotel in downtown Washington, authorities said, after police found a Bushmaster AR-15 assault-style weapon and dozens of rounds of ammunition in his vehicle.

Officers acted on a tip at about 1:50 a.m. and saw the weapon in plain view in the vehicle, which the driver had given to a hotel valet, police said. A Glock 23 handgun was found in the glove box, police said, along with 30 rounds of 7.62-millimeter ammunition and 60 rounds of 5.56mm ammunition.

Authorities would not say what they believe prompted the man, Bryan Moles, 43, a former Navy corpsman, to make the drive to the District or what they think he intended to do. A friend of Moles for 25 years described him as a hard-core supporter of President Trump who grew up with and owns weapons and might have been unaware of the District’s strict gun laws.

Police said the tipster had provided information that Moles made threatening remarks. D.C. Police Chief Peter Newsham would not characterize the remarks and said at a news conference that authorities “don’t have enough information right now to charge him with making threats.”

The chief thanked the tipster, whose identity was not revealed, for bringing a “potential tragic situation to a peaceful end.” Newsham added, “We’re going to do a thorough investigation into motive. I was very concerned about these circumstances.”

A spokesman for the U.S. Secret Service said agents concluded that Moles “posed no immediate threat to any Secret Service protectees.”

Moles, who lives in Venango Township, just outside of Edinboro, Pa., was arrested in his room at the hotel in the 1100 block of Pennsylvania Avenue NW, five blocks from the White House. Police said he was charged with possession of firearms without a license and illegal possession of ammunition.

Moles was being held pending an initial appearance in D.C. Superior Court on Thursday.

Several relatives reached Wednesday declined to comment.

Moles lives in a house with his wife and two sons off a curbed dirt driveway in the middle of a flat expanse about 20 miles south of Erie and 110 miles north of Pittsburgh, public records and interviews show.

Moles’s longtime friend, Lisa Della Ratta, 44, a nurse in Gulf Breeze, Fla., said that she did not know why he would have gone to the District but that he travels frequently. She said she does not believe he made the trip to harm anyone.

“He’s got an odd sense of humor,” said Della Ratta, who has known him since high school. “But if he was going to assault anyone, we would know. It wouldn’t be ambiguous. He grew up in rural Pennsylvania. He lives on a lot of land. He grew up shooting guns. We all grew up shooting guns. ... He probably didn’t know you couldn’t take guns into the District.”

The Trump International Hotel in Washington. (Alex Brandon/Associated Press)

On Facebook and LinkedIn pages that appear to be his, Moles lists himself as having been in the military, a physician and the current head of a nonprofit dog-placement facility called Boro K9 and Service run out of his home. The website says the organization places dogs with veterans and first-responders with post-traumatic stress disorder.

The social media sites that appear connected to Moles list Saint Vincent Hospital in Erie, Pa., as the most recent hospital at which he worked.

Della Ratta also said he worked there as a doctor. Dan Laurent, a spokesman for Allegheny Health Network, which runs the hospital, said a Dr. Bryan Moles worked as an emergency room doctor at Saint Vincent’s until 2013 but could not confirm whether that was the same person as in the D.C. incident

A Bryan Moles is licensed as a physician in Pennsylvania through Oct. 31, 2018, state records show.

According to the U.S. Navy, Moles enlisted in 1992 and served until August 1996 as a hospital corpsman at Camp Lejeune, N.C. He served in the reserves until 2006 as part of a surgical battalion out of Erie.

He worked at the Naval Hospital in Cherry Point, N.C.

Newsham said the sequence of events unfolded quickly, with D.C. police and the Secret Service learning about the tipster’s concerns at about 12:30 a.m. Wednesday. The chief said the information was relayed by Pennsylvania State Police, who provided a description of Moles’s vehicle and said Moles may have been headed to the Trump hotel.

Police informed hotel security workers, who quickly found the vehicle in the garage, Newsham said. Law enforcement searched it for potential hazards and found the weapons. Police said Moles was arrested without incident and was interviewed.

A spokesman for Pennsylvania State Police said his agency received information on Moles “that he was possibly in Washington, D.C. with weapons. We immediately contacted local authorities in Washington and related that information.”

Ryan Tarkowski declined to describe the information or say where it originated.

Della Ratta said that if Moles had planned violence, “why would he give his vehicle with guns in it to a valet, and then check into a hotel without his guns?”

Jennifer Jenkins and Spencer S. Hsu contributed to this report.