A “ground shaking” explosion that occurred at a Lake County industrial complex Friday night sent at least four people to the hospital, authorities said, and crews were still working to snuff out the flames just after midnight.

On Saturday morning, a press conference was held and according to fire marshals, officials found the structure too unstable for crews to continue to search.

According to law enforcement, three missing bodies are unaccounted for and a search continues as police said it could take a couple of days to pull the structure apart.

A Twitter user posted video of what appeared to be the massive blast which occurred in the 3700 block of Sunset Avenue in Waukegan shortly before 10 p.m. A fire official said the decimated structure was home to a business called AB Specialty Silicones. Waukegan fire Chief Steven Lenzi said four people were sent to the hospital but did not provide their conditions. Two were taken to Advocate Condell Medical Center and the other two were taken to Vista Medical Center-East, he said.

Waukegan police Cmdr. Joe Florip said a search and rescue operation was underway for other second-shift workers who may have been in the plant. There is no hazardous material concern for the debris scattered across the streets and in the air, officials said.

Sir Please find the footage from my outdoor cam pic.twitter.com/YgIdWPaeTG — Bhushan (@ibhushanjoshi) May 4, 2019

“If you have first-hand knowledge of the incident please call your local law-enforcement,” the Lake County Sheriff’s Department said. “If you’re not in danger and don’t have info, please don’t call 911.”

STAY OUT of the area of Sunset Avenue from Green Bay to Delany, Waukegan!! Please allow first-responders to conduct operations!! Area first-responders are on the scene of an explosion/building fire. — Lake County Sheriff (@LakeCoILSheriff) May 4, 2019

Before official information trickled out, Twitter users from all over the Lake County area were vexed by the “sonic boom,” as one person described it. Users from as far away as southern Wisconsin reported feeling the shockwave.

Emily Laughlin lives in the area and snapped photos of a large emergency response near the Waukgean/Gurnee border. She said authorities near Northwestern and Sunset avenues were telling cars to turn away from the burning husk of the silicone facility.

“Something exploded,” she said in a phone interview. “It looked like it was a building but they stopped everyone from getting closer.”

Nearly 1,000 Lake County residents were without power and viewers calling NBC 5 said windows in homes were shattered throuhgout the area.

No other information was immediately available.