© Louisiana State PoliceA tank containing naphthalene burns at Calcasieu Refining.
Evacuations and shelter-in-place orders remained in place for residents and businesses around a lightning-sparked tank fire that sent a plume of smoke over Lake Charles, Louisiana, on Saturday.

By evening, Louisiana State Police determined a lightning strike was the cause of the single-tank fire at the Calcasieu Refining Co. tank farm in Lake Charles shortly before 2 p.m., according to the department.

The company refines crude oil, operates a pipeline, and runs a barge transfer facility for oil products.

No injuries have been reported. The refinery did not answer phone calls seeking comment.

Evacuations were ordered Saturday as a fire burned at Calcasieu Refining Co. near Lake Charles, La. Louisiana State Police

Mandatory evacuations were in effect for those as far as a 1.5 miles from the tank farm. The outer boundaries of a shelter-in-place order have been reduced from 5 miles to 3 miles, according to the Lake Charles Fire Department.

The fire was still burning around 10 p.m., local time, state police said.

Dick Gremillion, director of the Calcasieu Parish Office of Homeland Security and Emergency Preparedness, said about 70 residents of assisted living facilities were among the people displaced, NBC affiliate KPLC of Lake Charles reported.

A shelter has been opened at the Burton Coliseum for people who have to evacuate, Gremillion told the station.

Lightning spidered across the region as a front of unstable air moved east and produced severe thunderstorms, hail and the threat of flash flooding, according to the National Weather Service on Saturday.

In an earlier statement, the fire department described the blaze as a "crude oil tank fire."

Port Director Ricky Self told KPLC that the grounds were home to another fire Thursday that may have started in an area where motor oil was stored for company vehicles.

It wasn't clear if the fires were related.