An explosion at a chemical plant Friday that could be heard 20 miles away caused a large fire and sent up massive clouds of smoke. No injuries were reported.

Several tanks and a building were on fire at the Marcus Oil & Chemical plant (search), but officials did not know what caused the explosion or what was in the tanks, said Tommy Dowdy, a district chief with the Houston Fire Department.

Streets were closed off around the plant, but there were no evacuations. Dowdy said the three people on duty at the plant were not near the explosion.

Lenny Ogle, manager of a gas station half a mile away, said the explosion shot flames about 75 feet in the air.

"It shocked the whole neighborhood. ... First it was the explosion and then it was the fire and then another explosion," he said.

Houston Fire Department District Chief Phil Boriskie said a hazardous materials team was conducting an evaluation. He said there were no reports of chemical exposure.

Marcus Oil & Chemical, owned by privately held HRD Corporation (search), makes polyethylene waxes, according to its Web site.