Firefighters remain hospitalized following fiery explosion in downtown LA

A criminal investigation is underway Monday and two firefighters remained in ICU after a fiery explosion in the Toy District of downtown Los Angeles occurred over the weekend, fire officials said. 

The raging commercial building fire sparked inside a building on the 300 block of Boyd Street Saturday around 6:30 p.m. and left a dozen firefighters injured. So far, three firefighters have been released from local hospitals, while the nine others remain hospitalized with a range of injuries. 

RELATED: Multiple firefighters injured as DTLA building explodes into flames

The investigation is being conducted by the Los Angeles Fire Department, the Los Angeles Fire Department and ATF.

Get breaking news alerts in the FOX 11 News app. Download for iOS or Android.

While fighting the flames, firefighters reported hearing what sounded like a jet engine and immediately knew they had to get out.

The explosion rocked the neighborhood as pressurized gas cylinders of butane began blowing up and turning the fire into an inferno.

One by one, the firefighters escaped down a ladder engulfed in flames.

According to LAFD, the fire was believed to have started inside a warehouse that distributed smoking and vaping paraphernalia, including supplies for butane hash oil.

The area is known as “Bong Row,” due to the high number of cannabis supply businesses.

On Good Day LA Monday, LAFD Chief Ralph Terrezas detailed the harrowing weekend for the department.

He said the firefighters who remain hospitalized are in “good spirits,” and “on the right track to recovery.”

However, the road to recovery will be different for each, as they all suffered various degrees of burns. Some are minor, some are moderate and for one, those injuries are severe, he said.

On the investigation, "we’re going to uncover everything we can," he said.

By Monday morning, the department confirmed the fire started at “Smoke Tokes”, a wholesale distributor of smoking paraphernalia. The had another major fire four years ago, authorities said.

That fire also caused a series of explosions that the fire department later determined to be exploding gas cylinders but no one was hurt.

The investigation is ongoing.