A Springville couple was killed instantly in a head-on collision with a semi-trailer truck on U.S. 6 Tuesday.

Killed were:Don E. Curtis, 78.

Goldie Curtis, 74.

The Curtises were about 13 miles west of Helper at 2:30 p.m. Tuesday when their car was struck by an eastbound semi that had drifted across the yellow line, Utah Highway Patrol Trooper Grant Bean said.

The truck, driven by Gordon B. O'Harra, 50, Price, was driving under the speed limit, but the Curtises' vehicle crashed into it while moving about 60 miles an hour.

O'Harra was not injured.

The crash shut down U.S. 6 for several hours Tuesday afternoon.

The cause of the accident is still under investigation, but so far, alcohol does not appear to have been a factor, Bean said. O'Harra and the Curtises were all wearing seat belts.

No citations have been issued at this time, Bean said.