An explosion at a fracking site south of Pearsall injured three workers Thursday afternoon.

Just before 6 p.m., officials said the explosion knocked the top off one of an oil well, launching it 25 yards in the air. Heavy flames and black smoke could be seen from miles away. 

“All the oil spread and started burning on top of those frack tanks,” said Placido Aguilar, Pearsall Fire Chief.

Firefighters from Pearsall and Dilley used a combination of water and foam to attack the blaze. Aguilar said firefighters also monitored levels of hydrogen sulfide, which is a poisonous gas. By 8 p.m., firefighters finally had things under control.

“It’s always dangerous,” Aguilar said. “You had a well that was still going we had to shut down and several tanks we had to close valves to."

The extent of the three worker's injuries were unknown late Thursday, but police said all three men were conscious and breathing when they were taken to the hospital. The cause of the explosion was unknown.

Click here to watch some images from the explosion