A Provo man and a Salt Lake teenager were killed Sunday in separate accidents on I-15 - accidents the victims probably would have survived had they been wearing seat belts, the Utah Highway Patrol reported.

Killed:Mark T. Aaron, 22, Provo.

Jeffery Robinson, 16, Salt Lake City.

Aaron apparently fell asleep at the wheel of his southbound car about 1:30 a.m. The car left the roadway near the Lehi exit in Utah County and rolled several times, ejecting him, the UHP said.

A passenger, Erin E. Johnson, 21, La Hambra, Calif., apparently was saved by wearing her seat belt, the patrol said. She was in stable condition Monday at American Fork Hospital.

Robinson was killed about 8:30 a.m. when the car he was driving rolled, ejecting him.

Trooper John H. Jones said Robinson was driving north on I-15 near 16th North when he drifted off the right side of the freeway. It appears that Robinson then overcorrected, causing the vehicle to roll back onto the freeway. Robinson was thrown into the outside travel lane.

Jones said inexperience appeared to play a role in the accident. He said had Robinson not tried to turn back onto the freeway and instead slowed to a stop in the barrow pit, the car likely would not have rolled.

The vehicle appeared to be traveling within the speed limit and there was no alcohol or drugs involved, Jones said.