Three people died and four others were injured when a boiler at Loy-Lange Box Co. in St. Louis, MO exploded this morning. The explosion sent the boiler, about the size of a van, rocketing up through Loy-Lange’s roof and crashing down through the roof of laundry company Faultless Healthcare Linen a block away.

One person at Loy-Lange, 59-year-old Kenneth Trentham, and two people at Faultless Healthcare Linen, 43-year-old Tonya Gonzalez-Suarez and 46-year-old Christopher Watkins, were killed. Four others were injured, two of them critically. An investigation into the cause of the explosion is underway.

Both companies are in Kosciusko, a mostly non-residential neighborhood of St. Louis located between the historic Soulard neighborhood and the Mississippi River. Loy-Lange is located at 222 Russell Boulevard; Faultless Healthcare Linen is about 500 feet away at the corner of Russell Boulevard and South Broadway.

Three newly hired employees at Faultless were filling out paperwork in the office this morning when the boiler came crashing through the ceiling killing two of them and critically injuring the third who was pinned beneath the cast iron boiler that weighed at least a ton and was still hot when fire crews arrived at the scene, according to St Louis Fire Chief Dennis Jenkerson. The fire department’s Collapse Rescue Task Force was able to free that employee, who is hospitalized.

The city of St. Louis requires companies to have a licensed engineer on duty whenever boilers are in use. Loy-Lange has three such engineers, a city employee told the St. Louis Dispatch.