A new lawsuit accuses PECO, its parent company and the owners of a Bristol, Pennsylvania, nursing home of failing to prevent the gas explosion that rocked the facility days before Christmas, killing three people and injuring several others. 

Four people wounded in the blast are suing PECO and its parent company Exelon as well as the Bristol Health & Rehab Center and its owners Saber Healthcare Holdings and Saber Healthcare Group, for negligence they say led to the blast and the injuries, according to a filing their lawyers shared with CBS News Philadelphia.

The plaintiffs suffered catastrophic injuries in the incident, the lawsuit says. They are a former resident, two aides and an IT contractor, according to Saltz Mongeluzzi Bendesky, the law firm representing the plaintiffs.

A resident and a nurse on the staff died in the blast on Dec. 23. Bristol Township Police Chief Charles Winik said 66-year-old Patricia Ann Mero, a resident of the facility, died from her injuries nearly two weeks later on Jan. 5.

The lawsuit alleges the companies named were aware of a gas leak "that had been festering for days" at Bristol Health & Rehab Center and failed to fix the leak or evacuate residents and staff before the explosion. 

PECO workers were at the site when the explosion happened, and at least one of them was hurt. 

A gas odor was detected in the building at least 30 minutes before the explosion, but the building was not evacuated, the suit claims. 

In a statement, a spokesperson for PECO said, "We are a party to the National Transportation Safety Board investigation. We are fully cooperating with the NTSB and according to the NTSB rules, we are not permitted to comment on this matter."

A representative for the owner of the facility, Saber Healthcare Group, previously told CBS News Philadelphia in an email, "PECO was immediately notified of a gas smell and was on site investigating the matter for approximately 2 hours. The area where the smell was discovered was evacuated."

Saber Healthcare Group took over ownership of the facility on Dec. 1. In a previous statement, it said, "We have worked to improve and fix prior issues, and we will continue that work in the wake of this event."

PECO in particular failed to appropriately test, maintain and fix the pipeline that was leaking and warn residents and staff about the issue, the suit says. It also accuses the nursing home and its owners of negligence for not maintaining a safe environment and failing to address the gas leak and evacuate those inside the building.

The National Transportation Safety Board is leading the investigation into the explosion and is expected to release a preliminary report by the end of the month. Residents say part of their Bristol Township neighborhood has been taken over by authorities and investigators trying to determine what caused the explosion.

CBS News Philadelphia has reached out to Saber Healthcare Group for comment on the lawsuit and has not heard back.