Alcohol may have been a factor in a head-on crash that killed four women, all senior citizens, as they were returning home from a church dinner in southwestern Ontario Saturday, police said.

The women were travelling in a Ford Focus when a minivan heading in the opposite direction collided with their vehicle shortly before 7 p.m. in Chatham, about 270 kilometres southwest of Toronto, according to police.

Three women were pronounced dead at the scene while a fourth died en route to a hospital in Chatham. All were trapped in the wreckage and had to be cut from the car, police said.

The driver of the van, a 47-year-old Chatham man, suffered serious but non-life-threatening injuries and was taken to hospital.

"At this point alcohol is believed to have played a factor in this tragic accident," Insp. Ed Reed of Chatham-Kent police said in a news release on Sunday.

At that point, no charges had been laid.

Police said no names would be released until the victims' families were notified.