Calgary police are investigating an assault after a woman was taken to hospital in critical, life-threatening condition on Thursday morning.

Officers were called just before 9 a.m. to a home in Dalhousie in the 4700 block of Dalton Drive N.W., where they found the 37-year-old woman, police said.

Neighbours watched as paramedics brought the badly hurt woman to an ambulance.

"When we saw the mom come out unconscious on the gurney, it was gut wrenching," said neighbour Megan Parker, adding she was worried for the two children in the home.

Calgary police tried to locate the victim's husband, who was killed later that morning in a fatal pedestrian collision with a semi-truck on Highway 2 near Crossfield.

RCMP in Airdrie said the missing 46-year-old man was driving northbound on Highway 2 when he pulled over, exited his vehicle and walked into traffic. He was struck and killed by an oncoming semi.

"Despite the efforts of the semi driver to avoid a collision, the man was struck and killed," RCMP said in a news release.

Calgary police said they are not looking for any other suspects but are still investigating the domestic assault.

Police said no further information would be released to protect the privacy of the victim and her family.