HOUSTON – Two people were killed in Friday’s early-morning explosion at a northwest Houston manufacturing business, officials said. The blast shook much of the area around the blast site, damaging buildings up to a half mile away and leaving some residents at least temporarily displaced.

The explosion shook Watson Grinding and Manufacturing around 4:20 a.m., destroying several structures and pushing some nearby homes off their foundations, officials said.

“This is, in essence, a disaster area right now,” Houston Police Chief Art Acevedo said of the area surrounding the blast site.

Here’s what we know about the explosion and its aftermath:

What caused the explosion:

An investigation into what caused the blast is underway and may take months, Acevedo said.

What’s happening at the scene:

Houston Fire Department Chief Sam Peña said a multiagency cause-and-origin investigation will begin once crews are able to get into the facility. Local, state and federal agencies are involved in that investigation.

A secondary search of the nearly 200 homes surrounding the scene is underway, Peña said. The chief said cadaver dogs are being used to search for any other victims who may be in those homes and crews are also checking the stability of the structures.

Peña said debris from the explosion is being found at least a quarter-mile from the blast site. Both Peña and Houston Police Chief Art Acevedo said that residents who find debris in the yards should not touch it and should call 911 so that the evidence can be collected.

The Bureau of Alcohol, Tobacco, Firearms and Explosive has sent its National Response Team, which is a federal team made up of scientists, investigators, explosive experts and engineers.

“We just don’t know what happened right now, so we are going to take everything that was supposed to be in that building and put it back together,” said Fred Milanowski, the Special Agent-in-Charge for ATF Houston.

He urged residents living and working within a 2-mile radius of the explosion to check their property for debris, particularly if its metal. Residents who find debris in the yards should not touch it and should call 911 so that the evidence can be collected.

Acevedo said there is no evidence that terrorism was involved in the explosion. He also said there is no evidence that an intentional act caused the blast.

The chief said that as the investigation unfolds, it could be determined that negligence led to the explosion and that could result in criminal charges being filed.

Peña said the owner of Watson Grinding and Manufacturing is being very cooperative with investigators.

How much damage the blast caused:

Pena said at least 214 homes were damaged in some way and, according to an initial rough estimate, about 50 were destroyed.

The nearest neighborhoods, Westbranch and Carverdale, were damaged most severely, Acevedo said.

Damage to homes included broken windows and doors, and in at least one case, a collapsed ceiling. Shock waves shoved some homes off their foundations.

One man described the aftermath in his neighborhood as a “warzone.”

“(The explosion) knocked us all out of our bed, it was so strong,” said resident Mark Brady. “It busted out every window in our house. It busted everybody’s garage door in around here … and closer toward the explosion over here, it busted people’s roofs in and walls in, and we don’t know what it is … It’s a warzone over here.”

Another resident said her ceiling collapsed in on her mother who was asleep at the time. She said a neighboring family came to her aid.

Can homeowners in the area get back into their homes?

Police at some point Friday cut off access to the damaged Westbranch and Carverdale neighborhoods, hoping to ward off potential looters.

But residents with identification were allowed back into those areas Friday afternoon, Acevedo said.

"We want people to come back (partly) because we do want people to board up" their damaged homes, the police chief said.

What are the recovery efforts underway for the residents impacted?

The Restoration Team, founded by several churches after Hurricane Harvey, sent out volunteers Saturday to help secure hundreds of homes that are exposed following the impact of the explosion nearby.

“We are focusing on securing exteriors of the structure so that weather tonight won’t get inside the home,” said director Trevor Barnett.

Mayor Sylvester Turner also visited with residents in the neighborhoods hardest hit by the explosion Saturday afternoon. He said he wanted to reassure residents that the City would do all it could to assist.

“We want to let them know they are not going to be forgotten. We are going to be here, and we are going to do anything to help get their feet back on the ground,” Turner said.

What we know about the victims killed in the blast:

The two men who died in the blast were Frank Flores and Gerardo Castorena, both employees of Watson Grinding and Manufacturing, Houston Fire Chief Samuel Pena said.

Flores and Castorena were the only employees on the property at the time of the explosion. They had arrived early ahead of their shifts to workout at a gym on the property, Peña said.

Friday night, Watson Grinding and Manufacturing issued a statement about the explosion. It reads in part:

“We are saddened by the tragic passing of our coworkers, and our deepest sympathies are with their families for their profound loss,” officials with the company wrote. “We are working diligently to address the situation and cooperating with the federal, state and local authorities investigating the accident. We are extremely grateful for the brave efforts of first responders who were on the scene immediately, and we will continue to give our full cooperation and support to their efforts.”

Officials with the Houston Fire Department treated two neighbors near the blast site who suffered non-life threatening injuries and 18 others checked themselves into area hospitals with injuries related to the explosion.

What’s next for Watson Grinding and Manufacturing:

The northwest Houston manufacturer suffered significant damage from the explosion, which destroyed several structures in the business compound. It’s unclear if, or when, Watson Grinding and Manufacturing will reopen.

Hours after the explosion, the first lawsuit was filed against the company on behalf of a homeowner whose property was damaged. The homeowner claims most windows were blown out, doors were damaged, walls were cracked and the foundation of the home was fractured. The homeowner is suing the company for more than $1 million.

The State Bar of Texas issued an alert Friday warning about reports of possible barratry — which is the unlawful solicitation by a lawyer or someone working for a lawyer seeking clients without a prior relationship.

Online records of the US Occupational Safety and Health Administration show the company was fined in 2013 for a serious violation related to the control of hazardous energy.

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