Two sisters, an 11-year-old friend and one adult died in a massive New Jersey fire that may have started inside a soda machine in a store where they were shopping and spread, the mayor of Elizabeth said Tuesday.

An 8-year-old girl, Daniella Marquez, her 10-year-old sister, Paola Marquez and an 11-year-old friend, Elizabeth Correas, died in the Monday evening blaze in the store at the corner of Elizabeth Avenue and Jacques Street. Officials say the sisters and their mom, Merlin Vasquez, had been shopping when flames erupted and tried to escape through a rear stairway, but encountered a metal cage surrounding the area and no exit. The bodies of the 8- and 11-year-olds were recovered Monday night; Paola was found under debris the next morning.

Their mother remained hospitalized in critical condition Tuesday.

Authorities also found a 41-year-old woman, Candida Martinez del Reyes, Tuesday when they found the 11-year-old child. Both were discovered buried in debris, in the same area where the other victims were found the night before.

"They could see out .. but couldn't get out," Elizabeth Mayor Christian Bollwage said, adding the city is looking into an egress issue on the second floor and will investigate whether there was a building code violation.

Video from Chopper 4 showed smoke and flames pouring out of the building as fire raged Monday. The fire continued to grow, eventually being upgraded to five alarms as firefighters battled the inferno.

The fire remains under investigation.