Officials say the fire started at National Container Group, a plastic tote cleaning business on Almeda Road and Almeda Genoa.
Firefighters battling 2-alarm warehouse fire in southwest Houston
Fire units first arrived to the scene shortly after 6:30 a.m. Monday. The Houston Fire Department upgraded it to a second-alarm fire minutes later.
By 7:45 a.m., it became a four-alarm fire.
At one point, Houston Transtar cameras showed the thick, black smoke coming from the area.
Huge warehouse fire burning in southwest Houston
The company cleans the 250-gallon containers and then sends them back out to businesses. Although the containers come in empty, they may still have a residual amount of chemicals left inside them that authorities say could contain anything from bleach to organic peroxide.
4-alarm warehouse fire in SW Houston
About 200 firefighters worked to put out the flames.
Officials say two firefighters were sent to the hospital while working on the fire. One firefighter was transported for heat exhaustion and the other for chemical exposure. Both are expected to be OK.
While the fire burned, Meteorologist Travis Herzog says it created a "pyrocumulus" cloud that was visible from miles away.
No word yet on the exact cause of the fire.