UPDATE: The Wyoming Highway Patrol reports the accident involved 3 vehicles, two pickup trucks and a small SUV. One of the trucks was towing a horse trailer.

56-year-old Carol Plummer of Casper was driving the SUV south on Robertson when she apparently ran through a stop sign. She crossed Highway 257 and was hit broadside by a pickup pulling the horse trailer, driven by 48-year-old Damon Mason of Medicine Bow.

48-year-old George Rott of Casper was driving another pickup in the opposite lane, and hit the horse trailer.

He was pronounced dead at the scene, and Plummer died later at the hospital. 3 horses were also killed in the accident.

Two passengers, one in each pickup, were injured.

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A person and three horses died after a tractor trailer hit a truck hauling a horse trailer at Robertson Road and the West Belt Loop -- Wyoming Highway 257 -- Friday afternoon, according to news and social media reports.

There also were several injuries.

Wyoming Highway Patrol officials did not return calls Saturday seeking comment.

We will update this story when we have more information.