2 dead in huge explosion at Houston plant that sent debris flying a half mile

Two people were killed early Friday in a massive explosion at a plastics manufacturing site in northwest Houston that tossed debris as far as a half mile and caused extensive damage to nearby homes, authorities said.

The explosion happened about 4:30 a.m. inside a building at Watson Grinding and Manufacturing, which makes valves and provides thermal-spray coatings for equipment in various industries, authorities said. The building was reduced to burning rubble and debris, and some of the surrounding buildings suffered heavy damage to parts of their walls and roofs.

Killed were employees Frank Flores and Gerardo Castorena, Houston police chief Art Acevedo said at a Friday evening news conference. The two had arrived at their workplace early and were using its fitness gym when the blast happened, Mayor Sylvester Turner said.

Authorities believed there were no other fatalities but another 20 people were injured, two other warehouse workers and 18 others from neighboring homes and businesses, Turner said. None of the injuries were thought to be life-threatening.

Acevedo had said earlier that a family member of one of those killed was a U.S. Marine currently training at Camp Lejeune, North Carolina, and called on the Marines to let the man return to Houston.

Local and federal officials will be at the scene for the next three to four days working through the ruins to determine what caused the explosion, Acevedo said. Authorities don't believe the explosion was intentional though a criminal investigation is underway, he said.

Police went door to door urging residents to leave the area in case of possible toxic fumes but determined in the first few hours that no toxic fumes were detected.

The police chief said drones were being used to survey damage in the area and asked residents to call police if they spot any suspicious or relevant debris.

“Do a search around your own home and your own neighborhood, even if you’re a mile away from this location,” Acevedo said. “Look for any debris, any body parts, anything that may be related. If you find anything in your immediate home, in your yard, don’t touch it. Just call the Houston Police Department so we can respond.”

Houston Fire Chief Sam Peña said the explosion erupted at a warehouse at Watson Grinding and Manufacturing, a machining and manufacturing company that refurbishes plastic pallets.

He said hazmat teams were able to secure the valve on a 2,000-gallon tank of propylene that had been leaking. Propylene is a colorless gas used to produce chemicals in plastics, synthetic rubber and gasoline. It is highly flammable and can explode in a fire. People exposed to propylene can become dizzy and light-headed, and the gas can also cause liver damage.

Local TV showed numerous residents reporting broken windows and cracked ceilings from the explosion that one resident told KHOU-TV sounded like a plane crash.

Mark Brady, who lives near the blast site, told Houston TV station KPRC that the explosion “knocked us all out of bed.”

“It busted out every window in our house," he said. "It busted everybody’s garage door in around here … and closer toward the explosion over here, it busted peoples’ roofs in and walls in.”

This part of Texas is home to the highest concentration of oil refineries in the nation and has experienced a series of explosions in recent years, according to the Associated Press. Last July, an explosion at an ExxonMobil refinery in Baytown, east of Houston, left more than dozen people with minor injuries and put nearby residents under a shelter-in-place advisory for three hours.

In December, two blasts in the coastal city of Port Neches shattered windows and ripped the doors from nearby homes.

Contributing: Associated Press

This article originally appeared on USA TODAY NETWORK: Houston explosion: 2 dead in blast at plastics plant, homes damaged