Rock struck Amtrak train in Philadelphia

By the Associated Press | February 4, 2016 | 11:15 PM EST

PHILADELPHIA (AP) — Amtrak officials have determined a rock struck one of its trains in Philadelphia.

The Acela Express was headed to New York City from Washington with 201 passengers aboard on Sunday night when the rock cracked a window. Amtrak spokesman Craig Schultz says no one was injured, in large part, because of reinforced safety glass used on all Northeast Corridor trains.

It's not known if someone threw the rock at the train.

The train stopped at Metropark in New Jersey so inspectors could check the damage.

The incident occurred near where an Amtrak train derailed in May, killing eight people and injuring more than 200.