Surveillance footage from nearby businesses on Wyoming Avenue between Third and Fourth Streets shows an enormous fireball rising and engulfing both sides of the street. The propane tank soared 95 feet into the air and landed in a nearby yard.
On his front porch across the street, Angel Caraballo heard the boom and felt the flames.
"The fire caught me right here, on the side of the face," he said Wednesday afternoon. He rushed upstairs and into the shower to try to soothe the wounds, including a long, reddish burn down his left arm and blisters on his neck and ear.
Downstairs, his wife, who had been on the porch but was uninjured, pulled the family's garden hose as far out as it would go in an effort to quench the flames. But the hose couldn't reach the truck.
Those nearby told police that one of the women appeared to have been blasted from the truck. A SEPTA officer, first to arrive on scene, found people sprawled on the street, including a woman on fire. A 23-year-old man walking by the truck was also critically wounded, police said.
Four victims were being treated Wednesday at the burn center at Temple University Hospital. The 13-year-old girl is at St. Christopher's Hospital for Children. Five other victims were treated for minor injuries, police said.
The vehicle - which police said was licensed to operate as a food truck - was open for business at the time of the explosion.
Police on Wednesday said the 100-pound tank was one of two used to supply grills inside the truck. It was not in use at the time.
"It is believed at this time that a significant leak occurred in the unused tank," police said. "A propane vapor cloud then enveloped the truck, finding an ignition source at the grills."
The investigation is being conducted by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives' arson and explosives task force, and Philadelphia police detectives and fire marshals.
As food trucks have gained popularity in recent years, there have been similar explosions.
In 2011, the propane tank on a New York City food truck exploded after a car accident, burning two workers.
Then, in 2012, a propane tank exploded on a food truck at the Canadian National Exhibition in Toronto, causing $30,000 in damage. That blast was heard almost two miles away.
And three people were injured when a food truck exploded last year at a high school football game in Fresno, Calif. That blast was caused when gas escaped from a propane tank inside the truck near an open flame, investigators found.
A 2012 New York Fire Department study of food trucks found several common fire hazards that could cause explosions, including the presence of multiple propane cylinders, hot fryer oil and grills, compressed gasses, high-voltage electricity, and biohazards from unsafe sanitary conditions.
On Wednesday, residents of Wyoming Avenue said they were shaken by the explosion. They described Galdemez and her family as hardworking and friendly, fixtures on the street.
Residents said they were from Guatemala. Chapin is used by Guatemalans to refer to themselves. Parrillada is spanish for grilled fare.
"They were nice people," said Kenny Boon, who worked down the street from where the truck typically parked. "I feel real bad - they didn't know what happened to them."
Nate Raynor, Galdemez's next-door neighbor, said Galdemez and her daughter were frequently outside at 5 or 6 a.m., stocking the truck for the day's work. Sometimes, he said, they offered him food.
Surveillance video from a nearby business captures the explosion. Go to www.inquirer.com/feltonville