BOSTON -- There are new concerns about commuter safety in Boston after a double stabbing at the Back Bay MBTA station Wednesday night.

NewsCenter 's Gail Huff reported that the fight started on board one of the trains and then spilled out onto the platform just before 8 p.m.

A 911 caller told police that a man stabbed two male teenagers many times, then ran up the escalator.

Officials said one teen boy was in critical condition at Boston Medical Center, while the other suffered injuries that weren't life threatening. No other information was available late Wednesday on the victims.

Hundreds of passengers had to be directed to shuttle buses when the station closed for several hours after the attack.

It was the second stabbing in only three weeks at the Back Bay station. On Feb. 19, a West Roxbury teenager was stabbed nine times. With the help of surveillance cameras, police arrested three Boston high school students in connection with the attacks.

"We're going to think twice about coming here alone at night, especially at night," one commuter said.

"I do think that they're very brazen attacks, I mean, I wish there were a large police presence," said another commuter.

Police were interviewing witnesses and reviewing surveillance tapes to see if they can identify the attacker.