Updated

Authorities sought a driver Wednesday who fled on foot after his sport utility vehicle crossed a center line and crashed into a semi-truck, killing a 3-month-old passenger in the SUV who was being held in his mother's lap.

The 25-year-old mother was hospitalized with internal injuries. The truck's driver wasn't injured.

The mother reportedly speaks Mixteco, an indigenous language spoken in Mexico, and investigators were having trouble finding an interpreter, Leary said.

A search by helicopters and a sheriff's dog didn't find the man after Tuesday night's wreck on a highway in Washington state, and his identity remained unknown.

"The person who first arrived on the scene saw this baby...was kind of traumatized, and didn't get an accurate description (of the driver)," Washington State Patrol Trooper Keith Leary said.

Leary said empty beer bottles were found in the SUV.