A teenager was in custody Saturday following a fatal shooting at the Bay Fair BART station that prompted a shutdown of the area for seven hours, according to police.

The shooting stemmed from a feud between two groups, each with three to four people, around 12:21 p.m. that then led to a shoot-out in the station’s bus zone, police said.

Investigators said an innocent bystander, a 40-year-old man, was fatally shot during the gunfight.

The man was pronounced dead at the scene and a woman was also injured by the gunfire. She went to the hospital and her injuries were not considered life-threatening, according to BART police.

Police said they weren't sure if the victims were entering or exiting the bus when the shooting occurred.

BART officers arrested a 16-year-old male following the shooting, but an active search for up to seven other suspects was still ongoing.

BART investigators said the surveillance cameras mounted on the AC Transit bus were working.

Police said they are combing through that video, along with video from surveillance cameras at a BART station, to try and figure out what exactly happened.

The station was shut down at 12:50 p.m. Buses were used to connect passengers to the San Leandro, Bay Fair and Hayward stations. The station finally reopened just after 7 p.m.

After the incident, some BART riders expressed concern over their safety.

“On the weekends, I don't feel particularly safe on (BART) because there aren't as many trains,” said Ainsley Hernandez, a BART rider.  “Typically there are not as many people on BART.  Typically, on the weekdays I feel safer because there's always the working commuter around.”

Investigators said they are still interviewing witnesses and reviewing videos and are still looking for up to seven possible shooters.