(CNN) –An explosion rocked a town in Illinois, leaving four people injured and several others unaccounted for, authorities said. The explosion happened at AB Silicones in Waukegan on Friday night, police said.
An unknown number of employees, likely less than five people, are still unaccounted for following the “catastrophic explosion” that hit around 9:30 p.m. local time, said Cmdr. Joe Florip, a spokesman for the Waukegan Police Department.
Four people, all employees, were transported to area hospitals with moderate to serious injuries.
“Fire, police, and paramedic personnel are working diligently at this scene,” the Lake County Sheriff’s Office tweeted. “Please stay out of the area and let the first responders work.”
The office tweeted earlier that it was aware of “a very loud explosion sound,” and “ground shaking.”
“While we have not been notified of any specific danger, it is recommended that local residents stay inside with windows closed with heat/air systems off at this time,” Joyce Mason, state representative for 61st District of Illinois, said on Facebook.
Authorities later said they do not believe there is cause for concern about air quality or a need to shelter in place.