By Jack Fink

PLANO, Texas (CBSDFW.COM) – A pair of ATF agents are helping the Plano Police Department investigate Monday’s house explosion that injured six people.

That development comes one day after police said the explosion may have been intentional.

The ATF said it has a local fire investigator helping the Plano Police bomb squad at the scene.

The ATF also has an engineer from its fire research lab in Maryland, which is dedicated to fire and arson investigations.

House explosion in Plano (Chopper 11)

The explosion happened around 4:45 p.m. Monday, July 19 in the 4400 block of Cleveland Drive near Park Boulevard and Coit Road.

Five of the six people injured lived next door to the house that blew up and on Thursday, July 22, a family friend said the woman who lives there is home from the hospital, but still recovering.

Her husband is still in the hospital. Their three children had minor injuries.

Their friend said they are grateful to the community for all the support.

A civil attorney told CBS 11 those who were hurt and whose homes were damaged could have a civil case.

“Homes don’t just explode, you know, even if it wasn’t a criminal conduct that caused this explosion. somewhere down the line, there was negligence or recklessness on the part of someone,” said attorney Seth McCloskey.

City building inspectors have placed red tags on six homes on Cleveland Drive and Boston Drive, meaning it’s unsafe to be inside them.

The city has placed yellow tags on three homes, which means while they have some damage, residents can still live in them.

The American Red Cross is helping those impacted by the explosion.

In the meantime, CBS 11 has learned eight homeowners have hired a law firm to conduct an independent investigation that will look for negligence on the part of the gas company which claims its system was operating properly on the day this happened.

While local and federal authorities continue their focus on a pile of rubble that was once a house on Cleveland Drive, some surrounding homeowners are focusing instead on a small pile of dirt a few yards away where they captured photos of work being done on an Atmos Energy pipeline.

“It’s inconsistent with some of the other stories that we’ve heard that there’s no leaks in the area,” said attorney Richard Mann.

Mann is an attorney with Ted Lyon and Associates, the law firm that represented the family of a 12-year-old Dallas girl killed in a natural gas explosion at her home in 2018.

James Pratt is one of the homeowners who hired the firm to investigate Atmos Energy’s claims that there were no leaks when the Plano home exploded Monday.

“Our bigger concern is are we safe are we not safe? Is it going to happen again? There are rumors flying around and they are inconsistent with what we are hearing,” said Pratt.

Homeowners have questions about this apparent work order on the gas line dated july 19th, the day of the explosion.

Atmos has yet to respond to questions about it.

But Atmos released a statement on Tuesday, July 20 saying after conducting safety checks it ruled out any involvement of its system and promoted a suggestion by Plano Police and fire that the explosion may have been an intentional act.

J.D. Miles contributed to this report.