Two people have died and two others are missing feared dead after an overnight explosion and fire at an Illinois silicone plant.

Waukegan fire marshal Steven Lenzi said one body was recovered on Saturday morning while another victim died after being taken to Loyola medical center in Maywood for treatment.

Crews at one stage have suspended their search for the other two workers due to concerns about the stability of the structure.

Nine employees were inside the plant when the explosion occurred at about 9.30pm local time Friday at AB Specialty Silicones in Waukegan, about 50 miles (80km) north of Chicago. A total of four workers were taken to hospitals and two declined treatment.

Lenzi said earlier Saturday it was “not likely” that any of the missing workers survived. He said it will take several days before crews are able to resume searching. The cause of the explosion is unknown.

He said the plant typically operates 24 hours a day, mixing chemicals and other materials to make silicone. The state fire marshal is investigating, along with the Occupational Safety and Health Administration.

Residents in the area said they heard the explosion and felt their homes shake. Five buildings nearby were damaged, with glass on windows and doors shattering, Lenzi said.

Nancy Carreno, who lives near the plant, told the Chicago Tribune the explosion didn’t break any windows but it was loud. She said electricity flickered then came back on.

Lenzi says more than 100 firefighters from at least 30 departments responded to the scene.

