Three people died and six seriously injured in a towboat explosion Friday morning at First Marine, the Western Rivers Boat Management Inc. shipyard at Calvert City, Ky., according to state police and local news media.

Marshall County authorities were notified of an explosion at 9:17 a.m. at the Tennessee River yard, bringing a massive response by police, fire and rescue agencies in the region. The three victims — Timothy Wright, 52, of Calvert City, Jerome Smith, 56, of Thibodeaux, La., and Quentin Stewart, 41, of Opelousas, La. — were pronounced dead at the scene. Among 20 to 25 people working on the boat six had serious injuries, some life-threatening, with several transported by ambulance and air evacuation.

State police were called to investigate, and said the explosion occurred inside a towboat as work was ongoing. The dead were not identified pending notification of their families, state police said. There was no early indication of foul play in the explosion, they added.

The Coast Guard responded to the scene and the federal Occupational Safety and Hazard Administration dispatched an investigator. The state police investigation is led by Detective Eric Fields, and the agency asked that anyone with information contact the Kentucky State Police Post 1 at 270-856-3721 or anonymously at 1-800-222-5555.

Western Rivers describes First Marine as the company’s foundation, originally created to rehabilitate older towboats and growing to include machine, fabrication and electrical shops, and a dry dock with 2,000-ton capacity. The yard also offers sandblasting and painting, rudder and tail shaft repairs, and complete carpentry services. The yard’s renovation services at its upgraded Calvert City facility are widely used by other towboat companies.