An Amtrak passenger train hit a large pile of rocks stacked on the tracks by vandals near Rathdrum, damaging and delaying the train, but causing no injuries.

The Empire Builder train hit the stack around 2 a.m. May 24 on BNSF Railway tracks near West Diagonal Road and North Ramsey Road, according to a Kootenai County Sheriff's Office incident report.

Images from the train's onboard camera at the time of the impact show the pile was more than 4 feet tall. There were also rocks placed along the rails for approximately 10 feet to the west of the pile, the report said.

Gus Melonas, a BNSF spokesman in Seattle, said Wednesday the railroad is continuing its investigation of the incident.

Marc Magliari, Chicago-based spokesman for Amtrak, said the collision caused a 25-minute delay. There were no reported injuries, he said.

"It's a malicious thing to do to passengers and the train crews who operate on that route," Magliari said. He called an Amtrak train hitting a pile of rocks on the tracks an "unusual occurrence."

Along with committing vandalism, those who were responsible also were trespassing on BNSF property, he said. He described the damage as cosmetic.

"We're hoping the sheriff's office and BNSF police can find out who did this," Magliari said. "We take this seriously with crews and passengers at risk."

The sheriff's office incident report said a BNSF police detective found several beer cans near the tracks. They were collected for fingerprint analysis, the report said.

The estimated damage to the train was $5,000.