One person injured in an explosion at an Illinois industrial complex died Saturday, marking the second death from the fiery blast as two others remained missing, authorities said.

The missing were believed to be under the rubble created by the Friday night explosion at AB Specialty Silicones in Waukegan, north of Chicago. Nine employees were in the building at the time, officials said.

Allen Stevens, 29, of Salem, Wisconsin, was one of four taken to a hospital after the explosion and was later transported to Loyola University Medical Center, where he died, said a Natalia Derevyanny, a spokeswoman for the Cook County Medical Examiner's Office.

One person, not yet identified, was killed at the scene, said Waukegan Fire Marshal Steve Lenzi.

The search for the two missing workers was suspended at nightfall Saturday and was scheduled to resume Sunday at 10 a.m., Lenzi said. Crew were using heavy machinery to clear the debris.

"The conditions are really rough in there," Lenzi said, according to the Associated Press. "There's a lot of damage. There was a lot of fire throughout."

The cause of the explosion was under investigation.

Waukegan is a city of around 89,000 in Lake County, about 35 miles north of downtown Chicago.