(Reuters) – A massive explosion at a manufacturing building ripped through a Houston neighborhood early Friday morning, injuring several people and damaging homes while sending out blast waves detected for miles around, officials and media said.

Smoke poured out from inside the structure in the predawn darkness about two hours after the blast as emergency vehicle lights flashed and first responders blocked access and checked for damage, aerial video from KTRK television showed.

No fatalities were reported, but one employee was unaccounted for, Houston Police Chief Art Acevedo said, according to the Houston Chronicle.

The moment of the explosion, around 4:25 a.m. CST (1025 GMT), was captured on a home security camera, also aired on KTRK, that showed a blinding flash in the distance, followed by a fireball.

Harris County Sheriff Ed Gonzalez said the blast was felt as far away as 14 miles (22 km), based on social media reports.

“(The explosion) knocked us all out of our bed, it was so strong,” Mark Brady told KPRC television. “It busted out every window in our house. It busted everybody’s garage door in around here. … It’s a war zone over here.”

Another neighbor identified only as Kim said her family was trapped in her home until rescued.

“The whole house is ruined,” Kim said. “The whole ceiling crashed down on all of us. We were all trapped in there, and a nice family came and helped us out. It’s trashed. It’s just trashed. … Every house was devastated.”

KTRK, the local ABC affiliate, said the blast appeared to have originated at Watson Grinding and Manufacturing, a machining and manufacturing company. The explosion took place on Gessner Road in northwestern Houston, city police wrote on Twitter.

“The owner of Watson Grinding tells us it was a propylene gas explosion, which sent two people to the hospital with non-life-threatening injuries,” KTRK reporter Marla Carter wrote on Twitter.

Propylene is a colorless, flammable, liquefied gas that has several industrial uses.

The debris field from the explosion spread about a half mile (1 km) wide, but there were no known toxic gases emitted from the blast, Police Chief Art Acevedo said.

The explosion damaged several homes in the area, the Houston Chronicle reported, showing pictures of homes with windows blown in and debris scattered.

At least two people had cuts on their faces after their windows were blown in, according to pictures published on the Chronicle website.

“This is still an active scene,” Houston Fire Chief Samuel Peña posted on Twitter. “We will advise of the possible cause of the explosion as soon as we have concrete info.”

A hazardous materials team was responding to the area and at least one person was taken to the hospital, the Houston Fire Department wrote on Twitter.

Mike Iscovitz, a meteorologist with the local Fox News channel, said the huge blast had shown up on local weather radar and was felt more than 20 miles (32 km) away.

“Radar clearly shows this brief FLASH of reflectivity from NW Houston,” he tweeted.

Houston, a major hub for the oil and gas industry, is the fourth largest city in the United States with a population of some 2.3 million.

(Reporting by Bhargav Acharya and Peter Szekely; Writing by Frances Kerry and Daniel Trotta; Editing by Alex Richardson Frances Kerry and Jonathan Oatis)