Washington (CNN) -- A North Korean submarine fired a torpedo that sunk a South Korea warship in March, investigators announced Thursday morning in Seoul, South Korea.

The conclusion came from a joint investigation committee comprised of American, Australian, British and Swedish, as well as South Korean experts.

The warship, the Cheonan, sank after an explosion ripped it in half on March 26 in disputed waters off North Korea. Forty-six sailors were killed or lost in the incident.

The United States has been "deeply and actively involved" in the investigation and "strongly supports it