Marissa Horn

USA TODAY

WASHINGTON — A series of assaults, robberies and other violent incidents in the subway and bus system here has police searching for an usual group of suspects: small groups of teenagers and young adults who they believe committed at least eight attacks since November.

The brazen attacks have riders wondering whether the city's popular Metro system is still safe to ride. D.C. Mayor Muriel Bowser recently proposed a bill that would create stricter penalties for those convicted of violent crimes on Metro trains and buses with perpetrators facing 50% more in fines and 50% more jail time.

But transit officials say despite the high-profile attacks, crime on the trains and buses that carry more than a million people a day has decreased. Crime was lower in 2014 and 2015 than in the preceding seven years, and was 23% lower than 2013.

“We recognize that there have been a handful of well publicized assaults involving juveniles in recent months,” a Metro spokeswoman, Sherri Ly wrote in an email.

In the latest incident, one witness said four teens allegedly set off a fire extinguisher and smoke bombs early Wednesday on the Metro's Red Line near the Rhode Island-Brentwood station.

Ly confirmed in an email that a fire extinguisher discharged. She would not say who or what set off the extinguisher.

Since November, police have recorded at least seven assaults on Metro lines, and another assault close to a Metro bus stop.

The first attack happened just before Thanksgiving. Joseph Cowart, 43, and his partner, Calvin Lawrence, 48, were traveling on the Green Line to their home in Gaithersburg around 1 a.m. on Nov. 22 when as many as a dozen teenagers attacked Cowart.

“When I first noticed something was going on, they were taunting [Cowart],” Lawrence said. “The girl hit him in the head and the boys came out of nowhere – I ran in the middle of those 12 kids to help him up and they dispersed.”

Lawrence said the teens called Cowart gay slurs. The Metro train operator, he says, ignored repeated calls for help as the train traveled several more stops.

“I ran out for help at the next Metro stop and it was a ghost town, there was no one there to help,” he said. “[Cowart] hit the button and alerted the driver and all the driver said was 'OK' and that was it – he didn’t give us any instruction or he didn’t say hold tight we are going to go five stops.”

The attack, first reported by the Washington Blade, landed Cowart in the hospital with head trauma and set back on his recovery from a stroke that occurred more than a decade ago, Lawrence said. Cowart no longer feels comfortable riding Metro, he said.

The couple has set up a GoFundMe page to help with the medical costs caused by the attack, he said.

Another attack occurred on Dec. 21 during the evening rush along the Red Line between Union Station on Capitol HIll and the NoMa-Gallaudet University stops. Lori Kaplan, the wife of the victim, said her husband suffered a broken jaw and traumatic brain injury from the attempted robbery.

Kaplan, senior director of audience insights at NPR, said she and her husband usually met on NoMa’s platform after work, and he had texted her about the group of kids prior to the attack. He has yet to return to work and has not taken the Metro since the attack, Kaplan said.

“When I ride the metro, I am hyper-vigilant and aware of my surroundings,” Kaplan wrote in an email. “Several colleagues have told me that they have stopped riding Metro after the slew of winter assaults.”

Other attacks include:

An assault Dec. 27 of a 19-year-old man at the Pentagon City station;

An assault on a 15-year-old boy and two of his friends at the Mount Vernon Square Station by eight teenagers a on New Years’ Day, according to Metro officials.

A robbery at Metro bus stop near Trinity Washington University. University President Patricia McGuire said six to eight girls attacked a female graduate student around 6:30 p.m. on Feb. 4, stealing her cell phone and other items. The student returned to school the following week, McGuire said. “She was shaken up but she’s OK.”

Police have made arrests in at least two attacks. Police arrested a juvenile for alleged attack a couple Jan. 2 at the Metro Center station, Metro officials said. Police arrested an adult for a Jan. 5 attack at the U Street Street/African-American Civil War Memorial station