A powerful explosion ripped through a chemical plant in Illinois injuring four people, with three others still unaccounted for, fire officials said Saturday.
The blast took place at a silicone plant in Waukegan, 40 miles (65 kilometers) north of Chicago, late on Friday night.
A “very loud explosion sound and ground shaking” were reported in the area, Lake County Sheriff department wrote on Twitter.
Fire, police and paramedic personnel were dispatched to the scene, it said.
Nine people were believed to be in the building at the time, said Steve Lenzi, fire marshal for Waukegan fire department.
Four were taken for treatment at nearby hospitals while two were not injured.
“We are unable to account for three subjects at this point,” Lenzi told a local ABC affiliate.
The fire has been extinguished at the site, he added.