Interim BART Police Chief Ed Alvarez said there was no danger to passengers because it “was a fight involving two individuals that engaged each other.”
He said transit officers entered the train at the next stop in Hayward, Calif., about 16 miles south of Oakland, after several 911 calls came in and found the victim bleeding. He later died of his injuries.
"Our thoughts are with the deceased and his loved ones," BART said in a statement on Twitter.
Officers arrested the suspect after searching the area.
The station was closed for several hours while officers investigated, BART said.
In July 2018, an 18-year-old woman and her sister were stabbed in an unprovoked attack by a felon on parole at an Oakland BART station.
Nia Wilson, 18, died in the attack.
Wilson’s family has blamed BART for failing to keep the trains safe for riders.
A BART spokesperson said the agency prioritizes safety.
The Associated Press contributed to this report.