It was a deadly weekend on Saskatchewan roads after seven people were killed in four separate crashes.

Around 4:20 p.m. Sunday, RCMP responded to a fatal collision involving four vehicles on Highway 6, about five kilometres south of Spalding, Sask.

A car was stopped in a construction zone when it was rear-ended by a semi-trailer, police said.

The car was pushed forward into a pickup truck, which then struck a highway flag person before colliding with a construction pilot vehicle.

The three people in the car – the 17-year-old male driver and two males passengers, ages 14 and 15, all from Carrot River, Sask. – were pronounced dead at the scene. Their names have not been released.

The flag person, a 21-year-old B.C. man, was flown to hospital in Saskatoon by STARS air ambulance with critical injuries. His current condition is not known.

The drivers of the semi, pickup, and pilot vehicle were all taken to hospital in Melfort with minor injuries and were later released.

So far, no charges have been laid.

Earlier Sunday, two people were killed in a collision on Highway 18, about 12 kilometres west of Estevan.

Mounties say it appears a vehicle entered the westbound lane of the highway and collided with a semi-trailer loaded with fertilizer.

The vehicle caught fire after the collision and both occupants died at the scene. Their names have not been released.

The driver of the semi suffered minor injuries and was treated by EMS.

Another crash near Swift Current early Sunday morning claimed the life of a 15-year-old girl.

RCMP say it appears the driver of a pickup truck lost control of the vehicle on a gravel road about 15 kilometres west of Highway 4.

The truck entered the ditch and rolled several times, coming to rest on its wheels.

A 15-year-old girl died at the scene. Her name has not been released.

The 16-year-old female driver was extracted from the vehicle and flown by STARS air ambulance to hospital in Saskatoon with serious injuries.

An 18-year-old woman who was a passenger in the vehicle was also seriously injured in the crash. She was taken by ambulance to Swift Current before being airlifted to hospital in Saskatoon.

And late Saturday afternoon, a 20-year-old man was killed in a single-vehicle rollover on the Okanese First Nation.

The man died at the scene after he was ejected from the vehicle, RCMP said. His name hasn’t been released.

Two other people in the vehicle were taken to hospital with non-life threatening injuries.

A third passenger left the scene but was later located by police.

Alcohol is believed to have been a factor in that crash.