Who , causing delays and injuring the engineer last week near ? Detectives are "actively working" leads into the case, said Sgt. Les Trull of the Los Angeles County Sheriff’s Department, Metrolink Bureau.
He said the incident was "very serious," but described the engineer's injuries as "slight."
Trull said the guilty party could face a felony sentence of a year in jail and a $2,000 fine.
"It left the commuters stranded until Metrolink could get a relief crew in there," Trull said. "Most of these individuals, especially in the afternoon, they just want to get home and get on with their life. Unfortunately someone doing a malicious act like this, it delayed them for awhile and it could have seriously injured the engineer."
The engineer, whose face was cut when a rock shattered the train's windshield, was treated "and is now resting at home," Metrolink spokesman Scott Johnson said Friday.
Near the time of the attack, a group of three or four teen boys were seen throwing rocks at kids near Bart Spendlove Park, according to the police blotter. One , police said.
Neither Metrolink nor the Orange County Sheriff's Department would confirm a connection between the rock and the arrest.