A massive pipeline fire sent a column of fire looming over some Houston suburbs on Monday as emergency workers evacuated surrounding neighborhoods and tried to prevent a fire from spreading to nearby homes.

The fire in a 20-inch liquefied natural gas pipeline is burning out on its own, according to Dallas-based operator Energy Transfer. The company said the line had been shut down, but local authorities said it could take hours, possibly until Tuesday, for the remaining material to burn out.

At an afternoon press conference, local authorities declined to speculate on what caused the fire or what role a burned-out car near the fire might have played. Energy Transfer said in its statement that it was aware of “previous reports” that a car had hit valves, but did not provide further details, including the origin of those reports.

Firefighters were dispatched at 9:55 a.m. to an explosion that rocked neighboring homes and businesses in Deer Park and La Porte, about 25 miles southeast of downtown Houston, long the energy capital of the U.S. The plume of smoke could be seen from at least 10 miles away.

The only injury reported so far was to the firefighter, who suffered a minor injury, officials said.