Nearly three years after an explosion and fire destroyed two apartment buildings and killed seven people in Silver Spring, Md., the federal government finally released its official findings on the cause of the disaster, providing crucial information to survivors and family members of the victims who are seeking compensation and accountability for their losses.

The National Transportation Safety Board (NTSB), during a public meeting held Tuesday, adopted a final report that concluded an unconnected gas vent line owned by Washington Gas allowed natural gas to leak into a basement room at the Flower Branch apartment complex, where an unknown ignition source caused the explosion and fire on August 10, 2016.

The entire report, scheduled to be released in about three weeks, is expected to serve as evidence in a lawsuit filed by survivors of the disaster against Washington Gas and Kay Management, the apartment building’s management company. At Tuesday’s meeting, the NTSB released key findings from its investigation and a synopsis of the final report.

In addition to killing seven residents, including two children, the explosion and fire injured 65 residents and three firefighters at the Montgomery County, Md., apartment complex, located only a few miles north of the District of Columbia.

Since the disaster, Washington Gas and Kay Management have opted against settling injury and economic claims made by the survivors until the conclusion of the NTSB investigation, according to CASA, a nonprofit immigrant advocacy group based in Maryland that has been providing support for victims of the blast.

The ongoing NTSB investigation was used as excuse for delaying any accountability for the 2016 disaster, CASA spokeswoman Ingrid Paola Zelaya said in an email to DC Media Group.

“Now that we have overcome one of the more vexing excuses … we will definitely be advocating for a full implementation of the NTSB recommendations and the pursuit of criminal charges for those responsible,” Paola Zelaya said.

Lawsuits filed by victims against Kay Management and Washington Gas in November 2016 are pending in Montgomery County Circuit Court. The lawsuits, which have been consolidated into one case, allege that Washington Gas and Kay Management ignored tenants’ complaints about the smell of natural gas before the explosion and request damages and attorney fees. Kay and Washington Gas have denied the allegations in court filings.

The next hearing in the Flower Branch case is scheduled for December in Montgomery County Circuit Court, according to CASA.

“Instead of denying responsibility for the explosion, Washington Gas needs to move quickly to implement the recommendations made by the NTSB including auditing service data and increasing inspections in multi-family housing units that rely on natural gas,” Montgomery County Council President Nancy Navarro said Wednesday in a statement.

Implementation of the recommendations “may help prevent a catastrophe like this in the future,” Navarro said. “As president of the County Council I will be working with my colleagues on the council to provide oversight in order to ensure that tragedies like this are averted.”

After a similarly deadly natural gas explosion in San Bruno, California in 2010, federal prosecutors brought charges against Pacific Gas and Electric (PG&E), the operator of the pipeline. State regulators also imposed significant financial penalties on the gas utility company.

The California Public Utilities Commission fined PG&E $1.6 billion over the pipeline explosion—which killed eight people—and imposed significant other financial penalties against the company.

After a federal jury found PG&E guilty of six felony charges connected to the San Bruno disaster, a judge in January 2017 imposed a $3 million fine against the company, the maximum financial penalty allowed under law. The judge also ordered a five-year probation period, independent safety monitoring and 10,000 hours of community service, including 2,000 hours to be performed by PG&E’s executives.

The actions against PG&E came after the NTSB determined the disaster had resulted from a combination of PG&E’s shoddy maintenance and flawed record keeping, along with lax oversight by state regulators.

In response to the NTSB’s report into the Maryland disaster, Washington Gas President and CEO Adrian Chapman said in a statement released Tuesday that the company disagreed with the agency’s findings, the Washington Post reported. The evidence did not show a failure of its equipment, said Chapman, who added: “We also do not believe the NTSB sufficiently investigated the other potential causes of the explosion.”

Kay Apartment Communities President Clark Melillo said in a statement that the company accepts the NTSB’s findings, according to the Washington Post report. “There was a gas regulator failure and a disconnected vent pipe — equipment not owned or maintained by Flower Branch Apartments,” Melillo said.

The NTSB report contains a list of recommendations for Washington Gas, the state of Maryland and other agencies to implement in order to avoid a similar disaster. “The NTSB is not a regulatory agency and does not have oversight, therefore, it will be up those agencies that do have regulatory authority to act according the recommendations that were issued,” agency spokesman Keith Holloway said in an email to DC Media Group.

The NTSB’s release of the report will also allow federal and state agencies and prosecutors to move forward with their own probes into the disaster.

The Maryland Public Service Commission participated in the NTSB investigation but has not yet completed its review of the agency’s findings and recommendations released Tuesday. “Once that is complete, the commission will make a determination as to the appropriate next steps,” PSC spokeswoman Tori Leonard said.

Failed Gas Regulator, Unconnected Vent Line Led to Maryland Apartment Building Explosion: https://t.co/bjriQ15M3i — NTSB_Newsroom (@NTSB_Newsroom) April 23, 2019

In its report, the NTSB found that the probable cause of the explosion “was the failure of an indoor mercury service regulator with an unconnected vent line that allowed natural gas into the meter room where it accumulated and ignited from an unknown ignition source. Contributing to the accident was the location of the mercury service regulators where leak detection by odor was not readily available.”

At the NTSB’s meeting Tuesday, agency investigators provided an overview of the accident and explanations of the examinations conducted following the explosion. The agency also provided recommendations that could help prevent a similar disaster.

NTSB investigator Rachael Gunaratnam said the regulator and vent were owned and operated by Washington Gas and were the utility’s responsibility to maintain.

Gunaratnam also explained that Kay Management changed the lock to the apartment building’s meter room without making a new key available to the Montgomery County fire department as required by law. Firefighters who responded to a call about the smell of gas two weeks before the explosion were unable to get into the meter room.

“The NTSB’s investigation highlighted serious flaws in the inspection of service regulators,” NTSB Chairman Robert Sumwalt said Tuesday in a statement. “This tragic event could have been avoided if the necessary checks were done to ensure the safety of the building’s occupants.”

Along with aviation and railroad accidents, the NTSB investigates accidents involving the transportation of natural gas by pipeline.

Residents of the Flower Branch apartment complex had complained about the length of the NTSB’s investigation. Similar investigations typically take far less than two years. The agency’s investigation into the PG&E pipeline explosion in San Bruno took slightly less than a year, about 20 months less time than the Flower Branch apartment investigation.

“Regarding the length of the investigations, each investigation varies on timeliness,” Holloway said. “The time frame of 12-18 months is an estimate but not set in stone.”

“NTSB’s goal is to determine cause, and make safety recommendations which, if acted on, would prevent future tragedies from occurring,” he said.

Sofia Reyes, president of the Flower Branch Tenants Association, said the evidence presented at the NTSB meeting on Tuesday was “a reiteration of what we already knew and what we had time after time brought up to both Kay Management and Washington Gas.”

“I’m relieved to know that after two and a half years, justice will soon be served to those that perished during the explosion and the families that continue to live with the economic, physical and emotional burden of that night,” Reyes said.