LOS ANGELES — Seven Los Angeles Fire Department firefighters who were injured when a natural-gas-powered truck exploded in Wilmington are suing the manufacturer, designer, distributer, owner and driver of the vehicle, alleging negligence.

The explosion occurred around 7 a.m. Feb. 15 near Alameda Street and Henry Ford Avenue. A total of nine firefighters who had responded to a report of a vehicle fire were injured in the blast, two of them critically. All ultimately survived.

"It is unacceptably dangerous that a truck running on compressed natural gas can fail like this, exploding in the middle of a city street like a bomb as opposed to releasing pressure safely," plaintiffs' attorney Matthew McNicholas said in a statement. "This would not have occurred had the product not had hidden defects preventing the safe release of pressure."

The lawsuit was filed Tuesday on behalf of firefighters Andres Saenz II, Casey Dunn, Daniel Goen, Howard Weiserweaver, Ian Gallardo, Robert Ward and Tom Rodriguez. It names as defendants a series of companies involved in the design and manufacture of the vehicle and its compressed-natural-gas fuel system, along with the woman who was driving the truck that morning.

LAFD Capt. Erik Scott told reporters the morning of the explosion that the woman driving the truck had "noticed some abnormalities of the tanks," prompting her to stop and call authorities.

Within minutes of arriving on scene, one of the truck's two compressed natural gas fuel tanks exploded, injuring the firefighters, one of whom could be seen on video being violently thrown through the air by the blast.

A preliminary summary released in March by the National Transportation Safety Board determined that the driver had seen sparks in the truck cab that prompted her to pull over and call 911, but responding crews were unaware that it was a natural-gas-powered vehicle.

The short summary report made no conclusions about the cause of the blast.

Goen was the most seriously injured of the firefighters, remaining hospitalized until Feb. 26.

According to the NTSB summary, the driver was traveling south on Alameda Street and "noticed sparks coming from inside the cab, near the bottom of the passenger-side seat" and pulled over near the intersection with Henry Ford Avenue.

"The truck was fully engulfed in fire before fire department personnel arrived, and the firefighters were not aware that the truck was CNG-powered," according to the NTSB. "During the course of firefighting, the driver's side tank exploded, injuring nine firefighters."

The agency noted that "all aspects of the fire and explosion remain under investigation," and investigators are working to determine the probable cause, "with the intent of issuing safety recommendations to prevent similar events."

The suit alleges that the defendants negligently designed, manufactured and sold what amounted to a defective CNG fuel system. It also contends there was no adequate written warning on the truck that it contained CNG tanks, nor did the truck driver alert 911 operators that the truck was fueled by CNG.