ST. LOUIS ( – A fourth person has died following Monday’s boiler explosion in Soulard.

Thursday morning, the Medical Examiner’s Office said that 53-year-old Clifford Lee of St. Louis died at a St. Louis hospital Wednesday.

Around 7:45 a.m. Monday, a large industrial boiler exploded at the Loy-Lange Box Company in the 220 block of Russell Boulevard. The equipment, described as a being about the size of a van, shot through the roof of the building and reached a height of between 450 and 500 feet.

A substantial piece of the boiler traveled around 500 feet laterally, eventually crashing through the roof of the administrative offices of the Faultless Healthcare Linen building, located a block away.

Watch: Surveillance video shows Soulard boiler explosion

The initial explosion killed 59-year-old Kenneth Trentham, an employee of the Loy-Lange Box Company. Another Loy-Lange employee was seriously injured and is listed in critical but stable condition.

Eleven seconds after the initial explosion, a large piece of the boiler tore through the ceiling of the Faultless Healthcare Linen building. It struck two employees, identified as 43-year-old Tonya Gonzalez-Suarez and 46-year-old Christopher Watkins, filling out first-day paperwork, killing them both.

Lee was inside the Faultless building when the hot boiler, which weighed an estimated 1.5 tons, entered the building. He was reportedly trapped under the hot boiler. After being freed from under the boiler, Lee was taken to the hospital and listed in critical, unstable condition. He was pronounced dead on Wednesday.

A GoFundMe account has been set up by the family of Gonzalez-Suarez to help the two children she leaves behind.

Another GoFundMe account was set up to help the families of the victims by an organization called "Sons & Daughters of Soulard," made up of charitable and community-minded business leaders in Soulard.The City of St. Louis does not inspect commercial boilers. However, any business with a boiler must have a city-licensed engineer on staff whenever the equipment is running. Trentham was the engineer on staff at the time of the explosion. He had been licensed since 1996 and had renewed his license every year.

The boilers were installed in 1966 and 1968. According to company permits, they were manufactured by a company called Clayton. They are made of steel and the permits say all materials comply with code.

The incident has been classified as a commercial accident.

Read: Box company paid $12,700 fines for safety issues

Loy-Lange has paid fines for workplace violations three times since 2014, though officials say none were related to the boiler.

The company paid a $3,741 fine after an August 2016 inspection found holes in floors that prevented proper cleaning.

An inspection in November 2014 found defective equipment, including a forklift without lights and damage to some safety latches. The company paid $6,566.

And in February 2014, the company paid $2,450 for defective energy control procedures, such as not properly training employees to ensure machinery was turned off and powered down.

Officials say the company has since addressed those issues.

Photos: Explosion in Soulard | Mobile users click here

The Faultless Healthcare Linen Company issued the following statement regarding the accident: “Our concern first and foremost is for our affected employees and those of Loy Lange and their families.

We have been informed that a fire of unknown origin erupted this morning at the Loy Lange property adjacent to our Faultless Healthcare Linen plant at 2030 South Broadway; that material from the Loy Lange fire came onto a portion of our building; and that as a result there are said to be injuries and fatalities among our Faultless Linen employees. At this time, the extent of the injuries and the names of those injured or killed have not been released.

We immediately will be giving what practical help we can to our employees and their families. We are grateful to the firefighters and other emergency responders who have acted heroically in response to this tragic event.

We intend to update this statement when we have more information later this morning.”Download the KMOV News app

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