Locals living in Port Arthur, Texas, were told to take shelter after an explosion rocked the city’s Valero Port Arthur oil refinery.
Images from the site show smoke rising above the site.
The incident occurred late on Monday at 7:22 pm local time.
Sheriff Zena Stephens said there are no reported injuries and the explosion was likely caused by an industrial heater, CBS affiliate KFDM reported.
Port Arthur Fire Department confirmed the incident, adding “the type of incident is unknown at this time”.
“To ensure the safety of all residents in the vicinity in light of the recent explosion at the Valero Refinery, an immediate shelter-in-place is ordered,” said the fire department.
“For your safety, please remain in place until the all clear is given by emergency personnel,” they said.
Detailed information about the cause of the explosion has not been released.
The Valero Port Arthur Refinery employs around 770 workers acccording to its website and produces 435,000 barrels per day of crude oil, which is then processed into gasoline, diesel and jet fuel.
Port Arthur is a city with a population of about 56,000 and it is located at the southeast corner of the state.
The explosion has come at a time when the strait of hormuz has been closed by Iran.
The port is a critical piece of the US’s fuel supply chain.