OMAHA, Neb. (AP) — Authorities in Omaha say a dozen cattle roamed an Interstate after the semitractor-trailer that was transporting them turned over.

The cargo of cattle went free Thursday night near a lane that connects two major highways in central Omaha. The incident caused traffic delays that weren’t completely cleared up until early Friday.

The driver of the semi tractor-trailer, which was carrying more than 30 cows and bulls, says his vehicle tipped over after he tried to avoid another car that swerved. While some cattle never left the trailer, others took to the streets and halted traffic.

The Nebraska State Patrol and other officials helped block roadways to corral the cattle. A patrol sergeant says four of the animals were killed for public safety concerns. Five others were killed in the crash.