BERKELEY -- A 20-year-old transient faces multiple felony charges after he allegedly tried to rob a woman in the North Berkeley BART station Sunday night in a scuffle that left four passengers injured.

Bay Area Rapid Transit police were asking Alameda County prosecutors to bring four charges of attempted murder and one of robbery against Mark LaGrone, BART spokesman Linton Johnson said.

LaGrone allegedly had a knife when he tried to grab the purse of a woman on the platform around 7 p.m., Johnson said. Witnesses intervened, with three passengers, including the intended victim, suffering minor injuries. Johnson said a fourth passenger's injuries are "fairly extensive" and will require surgery.

All four have been released from the hospital, Johnson said. LaGrone was not seriously hurt in the incident.

Investigators believe the passengers stopped a serial robber in the Bay Area, Johnson said.

"We're grateful they stepped in to help this woman," he said, "in this instance. Not that we encourage people to step in in a dangerous situation. They didn't know he had a knife."

It was not immediately clear what type of knife LaGrone allegedly used.

Johnson said it is "very unusual" to have a crime committed on the platform of a BART station because stations have video monitors and the presence of riders usually deters potential criminals.

Johnson said the suspect also picked the wrong day to try to rob someone, because BART enhanced security on the fourth anniversary of the Sept. 11, 2001, terrorist attacks.

Johnson said BART police arrested LaGrone by responding quickly to the 7 p.m. incident and a tactical unit promptly prevented people from leaving the station in case additional suspects were at large.

The North Berkeley station was closed for more than four hours, re-opening at 11:07 p.m.