An Orem mother and her infant son were killed and four others injured, two critically, in a two-car traffic accident believed to have been caused by a stray deer, authorities said Saturday.

KILLED:Michele C. Hansen, 18, Orem.

Dustin Hansen, 6 months, Orem.

The victims' husband and father, Brett Hansen, 20, was driving south on U.S. 89 three miles south of Mt. Pleasant.

"That area is really bad for deer," said Utah Highway Patrol Trooper Terry Smith. "And what happened is the car from Colorado saw the deer and slowed down and the El Camino (driven by Hansen) didn't see the deer and then locked his brakes."

Hansen apparently lost control of the vehicle, crossed the median and into the opposite lanes, Smith said.

Hansen was in critical condition Saturday in LDS Hospital, a nursing supervisor said.

Richard Wertz, 39, Alamosa, Colo., was in fair condition and his wife, Anna Marie Wertz, 43, was in critical condition, both in LDS Hospital, with injuries suffered in the 7:18 p.m. Friday accident.

A passenger in the Wertz car, Judith Kawanabe, 8, was in stable condition in Primary Children's Medical Center.