HARRISBURG, Pa. (AP) -- Gasoline spilled out from an unsecured hatch on the top of the gasoline delivery tanker that overturned and ignited beneath an Interstate 95 bridge in Philadelphia a year ago, according to new details from federal investigators.

Video evidence obtained by investigators shows the cover to the 16-inch "manhole" was open when driver Nathan Moody arrived at a Wilmington, Delaware, terminal to refill the tank and it was still not properly secured when he drove away to deliver it to a convenience store in Philadelphia, about 42 miles (68 kilometers) away. The crash killed Moody and disrupted transportation along a vital interstate for weeks.

A "origin and cause" report by the Bureau of Alcohol, Tobacco, Firearms and Explosives issued in September but made public late Wednesday said the "combined opinion" of its investigators is "that the fire most likely originated when gasoline escaped" from the open manhole as the trailer overturned and nearly 2,500 gallons (9,460 liters) of mixed gasoline and ethanol began to spill out from a section of the tank and ignite.

The findings shed new light on the June 11, 2023, early morning crash that destroyed the bridge beyond repair and shut down the highly traveled north-south artery in both directions for a couple weeks until an interim patch that made use of lightweight glass nuggets was in place. A permanent bridge opened to traffic in November and the highway returned to normal operations last month.

The ATF report was included in a set of investigative materials released by the National Transportation Safety Board as it looks into the cause of the explosion. The NTSB's final report could be a year away.

An NTSB "human performance" report said the truck rolled over as it negotiated an off-ramp at what appeared in surveillance video from a nearby building to be a high rate of speed.

"Video footage of the truck at his previous stop indicated that the truck driver neglected to close the manhole cover at the top of the tank before driving away," the NTSB said.

The ATF said it is also possible the aluminum tank ruptured or vapor recovery elements were damaged, releasing gasoline or vapors, or that the vehicle's diesel gas tanks ruptured, or a combination of factors.

Moody's cousin, Isaac Moody, a truck driver himself, said Thursday he was unaware of the tanker manhole cover issue but knew Nathan to be a safety conscious driver who stayed up on regulations and training requirements.

"It's so easy for them to throw the blame on the trucker in almost every accident that happens," Isaac Moody said in a phone interview. "As soon as a trucker cannot defend themselves, they find all kinds of stuff."

An NTSB interview with Philadelphia Battalion Chief Theodore Quedenfeld said that early on, firefighters faced "a lot of fire coming out of the storm sewers from the runoff" and that eventually multiple manhole covers from storm sewers became projectiles, flying into the air from the pressure of exploding gasoline.

Firefighters had to shut down their lines for a time because they could not say for sure whether any of the storm sewers were feeding branches that would go toward a water treatment plant, he said.

There were "dozens, dozens" of explosions, he said.

"It seemed like you would get an explosion and then it would kind of snuff itself out, but the heat would, you know, cause it to reignite as soon as it got a little oxygen," Quedenfeld told the NTSB.

Philadelphia Fire Capt. Cary Boyd told the NTSB when his team first arrived on the scene "every square foot of that underpass was nothing but flame."

Later, Boyd said, "the manhole covers were popping and they were big manholes, they're not the little ones. So there was a tremendous amount of pressure there."

The NTSB documents also included a two-page policy issued in 2022 by trucking firm Penn Tank Lines Inc. of Chester Springs, Pennsylvania, that mandated pre-trip inspections of tanker manhole covers by truck drivers. That policy described the manhole covers as devices that will form a seal in case of a vehicle rollover and noted an incident a year earlier in which a cover had been left unsecured, "allowing leakage and causing an environmental spill."

Moody, 53, who lived in Willow Grove, Pennsylvania, was an owner-operator with a commercial driver's license since 2003, investigators said. He leased his truck to TK Transport Inc. of Pennsauken, New Jersey, which has been a Penn Tank Lines affiliate since 2001. Phone messages were left Wednesday and Thursday seeking comment from TK Transport, Penn Tank Lines and executives with the companies.

The section of I-95 carried about 160,000 vehicles daily before the crash.