PORTLAND — Amtrak is suing the Massachusetts company that owned the truck hit by the Downeaster passenger train last month in North Berwick.

The driver of the truck owned by Triumvirate Environmental Inc. of Somerville, Mass., was killed in the July 11 collision.

Amtrak claims the driver, 35-year-old Peter Barnum, of Farmington, N.H., ignored railroad crossing controls and warnings while crossing the tracks. Four passengers on the train suffered minor injuries.

Barnum was carrying a load of trash to an incinerator.

The Portland Press Herald reported that Amtrak isn’t seeking specific damages, but said the collision and subsequent service disruption cost a total of $3 million.

The suit was filed in federal court in Massachusetts.

A spokesman for Triumvirate declined comment.

The investigation into the collision is ongoing.