Four members of a family were killed in a two-vehicle collision late Thursday in northern Alberta.

The four people were in a Ford Focus that collided head-on with a pickup truck at 11:45 p.m. just south of Bonnyville, the RCMP said in a release.

Ivan Charles Paul, 51, and his common-law wife Frances (Stella) Yvonne Gadwa, 35, were killed along with Gadwas' daughters, Alexis Josephine Gadwa, 15, and Sarah Margaret Gadwa, 14.

All were residents of the Kehewin Cree Nation.

The driver of the pickup truck, a 42-year-old man from Bonnyville, was taken about 300 kilometres south to a hospital in Edmonton for treatment of his injuries.

Investigators believe drugs and alcohol may have been a factor in the crash.

There have been several fatal car crashes in Alberta this week. Three people were killed in a crash near Leduc and five people died on a highway in southern Alberta.