At the Potomac Avenue station, three people were shot and one Metro worker was killed

A gunman opened fire early Wednesday at the Potomac Avenue station in Southeast D.C., killing a Washington Metro mechanic and hurting three other people.

In a statement released Wednesday night, D.C. police said that Isaiah Trotman, 31, of Southeast D.C., was arrested in connection with the shooting. Trotman is accused of first-degree murder while armed, kidnapping while armed, and assault with a dangerous weapon (gun).

Ashan Benedict, the Executive Assistant Chief of the D.C. Police, said that a "series of separate events" started when the suspect pulled out a gun while talking to people on a Metrobus. Detectives think that the shooter followed a passenger off the bus and shot them in the leg before going into the station.

"He's walking around with a gun in his hand and talking to people at random, so he's obviously upset about something," Benedict told the media on Wednesday morning.

The gunman got to the platform and confronted a woman after shooting a second person in the leg at a fare machine. Benedict said that two Metro workers tried to help after seeing this, but one of them was shot and killed.

Metro said in a news release Wednesday afternoon that the worker who was killed was Robert Cunningham, 64, who worked as a mechanic in the power department of the system.

"On behalf of the Metro board, words can't describe how sad we are to hear about Mr. Cunningham's death," said Paul Smedberg, Chair of the Metro Board of Directors.

"We think the worker was very brave when he or she helped a customer who was being threatened by the shooter."

The suspected shooter then tried to get on a train, but people stopped him and took him into custody. Two people were being treated for leg wounds after what happened on Wednesday, and a third person was hurt in the finger.

At a news conference with Benedict and Mayor Muriel Bowser, Metro General Manager Randy Clarke called it a "brutal day" for the public transportation company and said he had talked to Cunningham's coworkers on site.

"It's really sad to think that someone came in today to do their job and then tried to help and protect someone who lives here, but that person died," Clarke said. "I just hope that we can all think about that and thank the public servants who work so hard for us every day."

The police were still trying to figure out why the events happened the way they did.

Bowser told the media, "We don't know much about this shooter right now, except that it was someone with a gun who caused yet another tragedy in our city." "Metro and I will work together to finish this investigation."

After a police investigation, the Potomac Avenue station opened again around 4 p.m.