On Friday, the Worland, Wyo., volunteer fire department was called to this crazy-looking blaze. At first, it looks like a pool of wind-blown water with some occasional flames lapping at the surface. Then you realize what you’re looking at is all flame.

This is a burning sulfur mound. If you’ve ever been to a large landfill or even driven past one, then you’re familiar with the smell of sulfur — rotten eggs (hydrogen sulfide). The sulfur burning in this video is what remains from the Texas Gulf Sulfur Plant that operated here in the 1950s, according to the Worland Fire Department.

Sulfur is also flammable and difficult to extinguish. In fact, a few books of the Bible use it to describe hell. You may be familiar with “fire and brimstone” — brimstone being burning sulfur. Not only are you subject to eternal damnation in inextinguishable flames, but it also smells like rotten eggs.

The smoke produced by this fire is very dangerous. When sulfur burns it produces sulfur dioxide (SO2), which turns into sulfurous acid (H2SO3) when it comes in contact with water. That means it can be deadly if you breathe it into your very moist lungs. You’ll know sulfurous acid by another name, too — acid rain.

The firefighter shooting this video is wearing a self-contained breathing apparatus (SCBA), which is why he sounds like Darth Vader. The beeping noise is part of the SCBA design. When a firefighter doesn’t move for a certain amount of time, the apparatus beeps. If he or she continues to stay still — signaling possible distress — it beeps very loudly to alert other firefighters that they may have a partner in danger.

The Worland Volunteer Fire Department posted the video on Facebook and explained how they controlled the situation:

The fire was burning in a “bowl” shaped area, allowing all runoff to be collected in the fire area. A minimal amount of water was used to cool the surface of the sulfur and reduce the temperature below the molten stage. … The deposits in rural Washakie County are leftover from the Texas Gulf Sulfur Plant that operated north of Worland in the 1950’s. Much of the sulfur is mixed heavily with soil and is not 100% sulfur concentrate. This is a type of fire that is not common but needs to be addressed and dealt with safely and quickly. Fortunately the WFD has Hazmat Technicians and we have an understanding of this as we deal with H2S [hydrogen sulfide] and SO2 [sulfuric dioxide] on a somewhat regular basis.