Madison County officials said it could be several weeks before they know what caused a head-on collision that killed two people in separate vehicles.

Sheriff Ron Richardson said the crash remains under investigation, but officials with his department still await the results of toxicology tests.

Gary L. Gates, 50, Anderson, was pronounced dead at the scene of the two-vehicle crash shortly after 1:30 p.m. Saturday in the 700 block of Broadway in Ingalls.

Gates was driving a 1998 Chevrolet S-10 pickup southbound on Indiana 67 when he left his lane and collided head-on with a northbound 1991 GMC truck driven by Alice Barger, 65, Fortville.

Gates died of blunt-force trauma to the chest, Coroner Ned Dunnichay said. Barger was taken by helicopter to Indianapolis’ Methodist Hospital, but succumbed to her injuries several hours later. Marion County officials have not yet released her cause of death.

Dunnichay said Monday it could be some time before toxicology test results are known.

“It’ll take a couple weeks to get the toxicology in on that,” he said.