There was a “large fire explosion” at the ExxonMobil Torrance Refinery in Southern California on Wednesday morning, according to the Torrance Police Department. The explosion, which happened shortly before 9 a.m. local time, prompted a shelter-in-place order for nearby residents, according to police, though fire officials said there was “no chemical release.”

According to police, everyone was accounted for after the incident.  The fire was “quickly extinguished” by both Torrance Fire and ExxonMobil crews, the department added.

Although police reported three minor injuries, ExxonMobil said in an emailed statement Wednesday afternoon that four of its contractors went to the hospital with minor injuries.

“Our top priority is the safety and health of our employees and neighbors,” the statement read. “Refinery personnel, working with the Torrance Fire Department, are conducting air monitoring at the refinery fence line and in the local community.” The company said that no harmful emissions had been detected.

Police said that air quality readings were “within normal range,” adding: “Air Quality Management is on site to evaluate this situation.” 

John White, who lives near the refinery, about 20 miles south of downtown Los Angeles, told the local NBC affiliate that he was having his morning coffee when “all of a sudden, the whole house shook” with the force of the explosion. “It was just phenomenal,” he said. “It definitely scared us.”

Soon after the explosion, dramatic photos of the aftermath began to emerge:

ExxonMobil promised to conduct a “thorough investigation of the cause of this event.”

According to the company, approximately 650 employees and 550 contractors work at the 750-acre refinery, which “processes an average of 155,000 barrels of crude oil per day and produces 1.8 billion gallons of gasoline per year.”

The refinery, the company says, “is prepared for emergencies with its own fully-equipped fire department, which trains regularly with the Torrance Fire Department.”

Torrance Mayor Patrick Furey told the NBC affiliate that the dramatic flaring emitting from the refinery after the explosion is a “safety measure.” It happens occasionally, Furey said, but he added that Wednesday’s flames were a little larger than normal.

[This post has been updated.]