It was a deadly weekend on Saskatchewan's roads, with four deaths in the past three days.

On Monday morning, a man driving a pickup was killed in a collision with a gravel truck near Wakaw, Sask. The driver of the gravel truck wasn't hurt.

On Sunday night, a 24-year-old woman and a five-year-old boy died following head-on collision with another vehicle near the town of Hague, Sask., north of Saskatoon.

Police say they believe one of the vehicles, a Honda Civic, was travelling the wrong direction in the southbound lane of Highway 11 and it collided with a Grand Cherokee.

"There was a vehicle upside down in the ditch. The passenger, I believe, of that vehicle was pronounced dead on scene immediately," said Derek Lamb, a paramedic who was at the scene.

"There was a child on the side of the ditch with bystanders doing CPR, and another patient trapped and pinned in the vehicle, and a couple … people that were walking around the scene that were involved."

Three other people were taken to hospital with serious injuries: two men, ages 22 and 31, and a two-year-old girl.

Debris from the crash was still in the ditch as of Monday, including a child's sandal, plastic toys and some fishing gear.

"I've received these calls before, where you're going to a collision ... and your dispatcher tells you that it looks like children are involved, and you're thinking to yourself, 'This is going to be my last day of work,'" said Sgt. Lindsey Darling of the RCMP in Rosthern.

Police said alcohol may have been a factor in the Hague-area crash.

In the third fatal traffic incident, a woman, 20, died after being in a crash Saturday morning near Ahtahkakoop First Nation.

Police said she was on a grid road near the reserve when her vehicle rolled and she was ejected.

She died while on her way to hospital. The passenger in the vehicle was treated and is expected to recover.

None of the names has been released.