Waukegan Fire Marshal Steven Lenzi said the heroic efforts of the men who died in a May 3 explosion at AB Specialty Silicones saved the lives of their co-workers. Nine people were in the Waukegan, IL plant when something set off a massive explosion.

Jeff Cummings, 57, of Kenosha, Byron Biehn, 53, of Union Grove, Daniel Nicklas, 24, of Beach Park and Allen Stevens, 29, of Paddock Lake were killed in the blast.

AB Specialty Silicones makes silicones that are used in adhesives, sealants and for a number of business sectors including medical and dental products, and food processing. Lenzi has described most of the processes the company uses to make its products as non-hazardous. But Biehn, Cummings and Stevens, who were mixing chemicals that night, realized something was wrong and warned others to get out of the building. Their heroic actions saved lives, Lenzi told ABC 7 Eyewitness News. Officials are still trying got to determine the cause of the blast.

The company plans to hold a memorial service at the site tomorrow.

Memorial angel statue

The explosion was followed by a massive fire that completely destroyed the building. Lenzi said the investigation is still open. They are waiting for information from several sources and still interviewing people. The U.S. Chemical Safety Board (CSB) sent a three-person team to the scene to begin an investigation of the explosion. The CSB is an independent, non-regulatory federal agency that conducts independent investigations of fatal incidents involving chemicals with the goal of improving safety.