North Dakota firefighters struggled early Wednesday morning against a huge fire at a Williston oil industry supply business.
During the night, 500-foot flames still rose above the city from Red River Supply.
The fire started early Tuesday morning.
No injuries have been reported.
Some explosions have been heard.
A half-mile radius around the fire was evacuated.
A state highway near the fire was closed.
Officials said the cause of the fire is under investigation.
Red River provides storage, blending and delivery of drilling fluids such as calcium chloride, calcium bromide, calcium nitrate and potash, the company website said.
It’s a family-owned business founded by Rich Vestal in the 1970s.
Red River also distributes rail spurs for loading and unloading crude oil, drill pipes and casing.
The North Dakota hazardous materials response team and the North Dakota National Guard were called in to fight the fire, along with firemen from three counties.
Early air sampling didn’t show an toxic materials in the smoke plumes coming from the fire, authorities said.
Sloulin Field International Airport in Williston was closed Tuesday morning because of the smoke but later reopened.