Authorities say a pregnant Washington state woman was shot in the face on Saturday by her 4-year-old son after the boy found a loaded, unsecured gun under a mattress.

The King County Sheriff's Office says the 27-year-old mother is eight months pregnant and was taken to Harborview Medical Center with life-threatening injuries.

Deputies say the boy's father put the gun under a mattress because he was afraid of recent crime in the neighbourhood.

Under a new state law, gun owners could face criminal charges for not safely storing a gun.

It's unclear who the gun is registered to.

KOMO-TV reports detectives will be looking into the case Monday to see if any charges will be filed.