FALMOUTH, Va. —  A man fatally shot his girlfriend, their two children and then himself, moments before a concerned relative stopped by to check on the family, the Stafford County Sheriff's Office said Tuesday.

Aaron P. Jackson, 24, used an assault rifle to kill Latasha Thomas, 23, late Monday in a mobile home they shared, investigators said in a news release.

Jackson then used a handgun to shoot the couple's two children, Nicole Jackson, 2, and Aaron Jackson, 18 months, and himself, investigators said.

Police said the adults died at the scene. The children, who were shot in their cribs, were taken to area hospitals where they later died, according to sheriff's office spokesman Bill Kennedy.

Authorities were called to the home in Walt Lou Trailer Park at 9:40 p.m. Monday after a relative who came to check on the family couldn't get a response, Kennedy said.

Police later learned Thomas had contacted the family member twice Monday complaining of being physically assaulted by Jackson, but called at 9:30 p.m. to say things were fine.

A neighbor reported hearing gunshots moments before the family member arrived, Kennedy said.

Click here for more from MyFOXDC.com.