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

Stephen McCausland, spokesman for the Maine State Police, said Trooper Barry Meserve shot and killed the man at an apartment at 278 Main St.

As is standard in any case involving a police shooting, Meserve has been placed on administrative leave with pay. The shooting will be investigated by the Maine Attorney General’s Office and Maine State Police.

Meserve is a 15-year veteran of the force.

McCausland said police were called to a third-floor apartment around 6 p.m. after receiving a report that a man had fatally stabbed his girlfriend.

The couple, whose names were withheld Wednesday night pending notification of relatives and positive identification, are believed to be in their 30s. They had lived in the apartment for two months.

McCausland said the couple lived in the apartment with two children, ages 2 and 4. The children were placed in the custody of relatives.

The state Medical Examiner’s Office will perform an autopsy on the victims’ bodies on Thursday.