CARY, N.C. — Authorities say two sisters died in a car wreck in Cary Friday morning.

The accident on U.S. Highway 1 in Cary killed Ethel Graves Cline, 67, of Randleman and her sister, Dorothy Graves Wall of Franklinville, who died later at WakeMed.

Also taken to WakeMed from the scene were Cline's other sister, Cristine Grace Chriscoe, 62, of Randleman and granddaughter Linda Marie Parks, 11.

Investigators believe that the accident was likely caused when the car Cline was driving crashed into a van while attempting to merge onto U.S. 1 just after 10 a.m.

Maria Osorio, 57, of Raleigh and Mario Guzman, 40, of Cary were in the van. Osorio was transported to WakeMed. Guzman was not injured.

Police do not believe speed was a factor.

Traffic was backed up for miles as crews worked to clear the scene. Both lanes of southbound U.S. 1 to traffic were reopened about three hours after the accident.

The state Department of Transportation is planning to expand U.S. 1 in that area to three lanes. Work is scheduled to begin in Spring 2005. It should take about two years to complete.