DENVER — Beer and asphalt spilled out of rail cars in downtown Denver Wednesday after a string of 34 freight cars crashed into parked locomotives, derailing four of the cars and damaging others.

No one was injured and nothing got into waterways, said Steve Forsberg, a spokesman for BNSF Railway. The railroad’s mainline operations were not affected.

Forsberg said a switch engine was assembling a train at about 4:30 a.m. when the crew lost control of the 34 cars, and they rolled downhill into two stationary locomotives.

A tanker car carrying Coors beer overturned and spilled its contents onto the yard, Forsberg said. Another car carrying asphalt was damaged and leaked.

Forsberg did not know how much beer and asphalt spilled.

The parked locomotives were heavily damaged, and an unknown number of freight cars were also damaged. Cost estimates were not immediately available.

Forsberg said it could take more than 10 hours to clean up the spill, remove the damaged rail cars and locomotives and repair any damaged track.

BNSF is based in Fort Worth, Texas.