Three horses died in a rollover crash early Thursday on Interstate 35E in downtown St. Paul, forcing the southbound lanes and some ramps to be closed for hours and traffic to be diverted.

A truck towing a trailer carrying five horses flipped on its side around 2:45 a.m. in the southbound lanes of I-35E at University Avenue, the State Patrol said.

The truck driver was not hurt, said patrol spokesman Gordon Shank. Another trailer was called in to transport two horses that survived, he said.

Traffic was rerouted from southbound I-35E to westbound I-94 as ramps to eastbound I-94 and Hwy. 52 were blocked.

The crash and several others in the backup made for difficult travel on southbound I-35E during the peak of the morning rush.

Complicating the commute, a multicar crash just before 8 a.m. blocked the westbound lanes of I-94 at Hwy. 52 for about an hour.

MnDOT crews had cleared the horse trailer and truck from the scene as of 10 a.m. but were still fixing guardrails damaged in the crash.

It was not immediately clear what caused the truck and trailer to roll. The crash is under investigation, Shank said.