MOUNT VERNON, Ohio (WCMH) — A man and a woman were found dead after a standoff and a shootout with Knox County deputies.

Deputies responded to a 911 call in the 10000 block of Busenburg Road in Howard Thursday morning. They encountered a woman who said she was injured by a man, according to the Knox County Sheriff’s Office.

The man and a deputy exchanged gunfire before the man released an unknown chemical, forcing the deputies to evacuate, according to the sheriff’s office. While the deputies were leaving, the man fired more shots at officers and their vehicles.

A standoff ensued that lasted for several hours, until both the man and a woman were found dead inside the home, according to the sheriff’s office. Two other people inside the home were safely removed.

No other details were immediately available.

The Bureau of Criminal Investigation was called in to investigate. Mount Vernon police, the Fredericktown Police Department, Ohio State Highway Patrol and Ohio State Highway Patrol’s aviation unit all responded.