Investigators say a Maine state police trooper shot and killed a man who was involved in a domestic violence homicide Wednesday night at an apartment in Old Town.

Alan Cleaver, Flickr

State, county and local police surrounded a three-story apartment building on Main Street in Old Town after a man called police to say he had stabbed his girlfriend. Two young children, ages 2 and 4, were in the apartment at the time and were released unharmed, according to the Maine Department of Public Safety.

The standoff ended when a state trooper shot and killed 28-year-old Christopher Ouellette. Trooper Barry Meserve, a 15 year veteran of the Maine State Police has been placed on paid administrative leave while the Maine Attorney General’s Office investigates the shooting.

State Police say 35-year-old April Haskell, who was pregnant with the couple's third child, was found dead in the apartment.   Haskell and Ouellette had been together for about six years, and had lived in the Old Town apartment for about two months.

Their two young children have been placed in the custody of relatives.