Northwestern Houston was rattled early Friday by an explosion at a manufacturing plant that left at least two people dead, authorities said.

The blast happened shortly before 4:30 a.m. local time at Watson Grinding and Manufacturing, a machining, grinding and thermal spray coatings company.

Houston Police Chief Art Acevedo told reporters at a news conference about five hours after the blast that his team will launch a criminal investigation into the deaths in partnership with other agencies.

“We have no reason to believe terrorism is involved,” he told reporters, adding that an investigation is department protocol.

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Flames fill the sky after a massive explosion rocks west Houston Friday, Jan. 24. Marie D. De Jesús/Houston Chronicle via AP

A 2,000-gallon tank of highly flammable gas that caused the explosion has been secured, Houston Fire Chief Samuel Peña said in a Friday morning news briefing. All valves that were emitting gas have been closed, he said.

The tank contained propylene, a very flammable gas, the owner of the plant told KTRK.

“We’re waiting for a final fire to burn off,” Peña told reporters. “Adding water could cause runoffs [of chemicals].”

There are no concerns about toxins in the air at this time, Peña said.

Nearby homes were shaken and some were damaged, with shattered windows, collapsed ceilings and a few crumbled structures, KTRK reported.

“[The explosion] knocked us all out of our bed, it was so strong,” Mark Brady told KPRC 2. “It busted out every window in our house. It busted everybody’s garage door in around here.”

Debris shot through the air, traveling as far as a half-mile from the blast site, Acevedo tweeted.

Peña told reporters that a strip mall adjacent to the plant suffered significant damage in the blast. He estimates that he and his crew will be surveying the area for as long as a week.

A Mormon temple has been designated as a temporary shelter, according to Houston Mayor pro tem Dave Martin. The city is trying to set up shelter and permanent housing for people whose houses are uninhabitable, he said.

Two schools in the area are closed for the day. Residents are being warned to take precautions, although no mandatory evacuation was issued, according to KHOU-11.

Acevedo said his employees have brought in personal drones to survey roofs and to get a better scope of the damage.

He also issued a stern warning to anyone caught looting in the affected area: “If you are caught, you will be charged to the full extent of the law. You will not get a slap on the wrist,” he said.

Acevedo and Peña requested that the public search their homes and neighborhoods for debris and body parts. If anything is found, they urge residents not to touch their discoveries but instead to contact authorities

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