A Nevada trucking company has filed suit again Amtrak and Union Pacific, claiming they failed to maintain a safe railroad crossing at the site where one of its drivers plowed into an Amtrak train last month, killing six people and injuring at least 20 others.

The Reno Gazette-Journal reports that in documents filed Friday in Reno federal court, John Davis Trucking Co. claims the companies didn't adequately warn drivers of oncoming trains.

Union Pacific and Amtrak representatives did not immediately respond to the complaint.

The Amtrak passenger train was en route from Chicago to the San Francisco Bay area on June 24 when Lawrence Valli's truck crashed through the crossing gates about 70 miles east of Reno, Nev., and into one of the cars.

Amtrak earlier filed suit against John Davis Trucking, alleging negligence in its training of the truck's driver.