PHILADELPHIA (KGO) --Surveillance video captured the frightening moment when a food truck blew up in Philadelphia.
The quick and violent blast was reported around 5:30 p.m. Tuesday in the city's Feltonville neighborhood.
"I heard the boom first and then the fire just came out of nowhere," said eyewitness Latoya Page.
A transit police officer who rushed to the scene immediately following the explosion says multiple victims were lying in the street, including at least one who was on fire.
The explosion happened outside an auto body shop.
On Wednesday, authorities issued a statement saying a leak from one of the two propane tanks on the lunch truck created a vapor cloud that was ignited by the cooking grills.
Authorities say five of the victims remain in critical condition, including the 42-year-old truck owner, her 17-year-old daughter and two other relatives, and a 23-year-old man.
Officials say the truck was licensed to operate and was open for business at the time of the explosion.
(ABC News and The Associated Press contributed to this report)