A three-person investigative team from the U.S. Chemical Safety Board will investigate an incident that killed four people and injured four others on April 3 at the Loy-Lange Box Co. in St. Louis.

According to initial reports, the incident took place when a boiler exploded at the plant, where one worker was killed. The force of the explosion launched the boiler into the air, where it flew approximately 500' before landing on a nearby laundry facility. Two members of the public, Christopher Watkins, 46, and Tonya Suarez-Gonzalez, 43, a married couple from St. Ann, Mo., died at the scene. A Loy-Lange engineer, Kenneth Trentham, 59, also died in the blast. Clifford Lee, 53, of St. Louis, died April 5 as a result of the injuries he sustained in the blast. All four victims were in the laundry office.

The CSB's investigation team arrived onsite at the Loy-Lange Box Co. on April 6. CSB investigators visited all three sites impacted by the April 3rd incident: Faultless Linen; Pioneer Industrial Corp.; and Loy-Lange Box Company.

While early reports called the equipment involved in the incident a boiler, the vessel that launched into the Faultless Linen building was a hot water storage tank. Also called a semi-closed receiver (SCR), the tank was part of a steam-generator system.

The SCR launched out of the Loy-Lange facility and into the Faultless Linen site, crashing into an office area. An initial examination found that the vessel appears to have landed top down into a room where three people were present. The three people in the office room were fatally injured.

Because the structural integrity of the Faultless Linen office area is still being assessed, the failure mode of the SCR is unknown. Currently, it is too dangerous to enter the room to conduct an in-depth examination.  The CSB has begun discussions with the appropriate entities on site to remove the equipment to allow forensic examination.

An initial assessment also found that an approximately 12.5' long pipe, which had been attached to the SCR, crashed through the roof of the Pioneer facility. It stuck in the roof and punctured an office ceiling, where it remained until the company removed it to temporarily re-roof the hole to protect the building from water damage.

The CSB is coordinating its investigation efforts with local emergency responders and other federal agencies and investigative entities.