Five workers were injured late Monday after an explosion at a chemical plant near Lake Charles, Louisiana.

There are no reports of any fatalities as of Tuesday. Two employees were transferred to hospitals in Hammond and Lafayette. Three of the five people injured were released from the hospital, according to Louisiana State Police Trooper Derek Senegal.

Authorities are unsure what caused the eruption.

The explosion happened at 11 p.m. at the Westlake Chemical plant in the small town of Sulphur. Joe Andrepont, a spokesperson for the company, told local news outlets that the plant produces ethylene and that it was undergoing maintenance at the time of the explosion. He said that the explosion was a flash fire and that the flames disappeared quickly.

American Fuel & Petrochemical Manufacturers said that petrochemicals like ethylene are important because they are used to make day-to-day products more efficient.

A video posted on Facebook showed the aftermath of the explosions with huge plumes of smoke in the sky.

One user commented in response to the video, “It shook my whole house. scared me.”