LOS ANGELES, California (CNN) -- A pressurized cylinder exploded at Universal Studios on Sunday, injuring two firefighters as they tried to fight a blaze that began earlier in the day, Los Angeles authorities said.
The fire destroyed buildings and movie sets at Universal Studios on Sunday. more photos »
Eight other firefighters were injured in the fire, which was expected to be contained by 4:15 p.m. (7:15 p.m. ET), said Ron Haralson, an inspector with the Los Angeles County Fire Department.
The explosion occurred about 2:30 p.m. (5:30 p.m. ET) near the video vault of the Universal Studios back lot. The vault was damaged.
The fast-moving, early morning blaze destroyed several movie sets and the King Kong exhibit.
Even so, officials still planned to go ahead with the 2008 MTV Movie Awards show at the site -- just north of downtown Los Angeles, adjacent to the Universal Studios theme park.
"The areas we are utilizing for our production were unaffected and the 2008 MTV Movie Awards will go on as planned. We're working closely with authorities to make sure everything operates smoothly," an MTV spokesman said in a statement.
The awards show will bring a parade of A-list stars to the park's CityWalk area. According to MTV's Web site, celebrities such as Tom Cruise, Will Smith, Sarah Jessica Parker, Justin Timberlake and Robert Downey Jr. likely will attend.
Universal Studios officials planned to resume normal business hours Monday, including the studio tour.
The fire destroyed an area called New York street, which includes movie set-style buildings designed to look like the cityscape of New York City. Hours after the blaze was reported, the roughly two-block area appeared charred and resembled a "disaster movie," said Los Angeles Councilman Tom LaBonge.
LaBonge said he could see the smoke from his Silver Lake home Sunday morning. "It looked like a bomb had exploded," he said. Watch choppers try to douse the fire »
Don't Miss KABC: Fire consumes soundstage
The blaze began around 4:45 a.m. (7:45 a.m. ET) and was contained initially by 9 a.m. Throughout the morning, large plumes of black smoke rose as the fire burned the vault containing hundreds of videos, said Ron Meyer, chief operating officer of Universal Studios.
"Fortunately, nothing irreplaceable was lost," Meyer said. "The video library was affected and damaged, but our main vault of our motion picture negatives was not."
The set of "The Changeling," a film recently directed by Clint Eastwood and starring Angelina Jolie, was "completely destroyed," Meyer said.
Another area called "Courthouse Square" also was destroyed, Meyer said. Numerous movies have been shot in that area, including several scenes of the 1985 hit "Back to the Future," Meyer said.
And two of the eight locations used by the CBS series "Ghost Whisperer" were affected, he said.
Fire inspectors had not determined what caused the blaze, said Los Angles County Fire Chief P. Michael Freeman. There were no reports of filming at the time of the fire.
All About Los Angeles
The backlot at Universal City Studios

The Los Angeles County Fire Department responded to a fully involved structure fire on the back lot of Universal City Studios in Universal City, California which occurred shortly after dawn. Reports indicate a fire and a explosion occurred around 4:45 local time. 

The fire continues to burn in the Universal Studios backlot, which is adjacent to the Universal Studios theme park. 

The "New York Street" sound stage was completely destroyed and the Courthouse Square backlot from Back to the Future, an exhibit on the movie King Kong, the video vault, and a ride known as the "Cyclone" were damaged. County fire inspector Daryl Jacobs said at least three blocks of movie façades may have been destroyed.

More than 400 firefighters responded to the three-alarm fire, with helicopters dropping water on the blaze in an attempt to contain it. Three firefighters suffered minor burns, one reportedly from smoke exhaustion. No other injuries have been reported. Several urban search and rescue teams were dispatched to the area.

Daryl Jacobs said that the firefighters ran out of water at least twice while battling the flames. "There was an issue with water, but that has been rectified," Jacobs said. "They are shuttling water in." He also said firefighters encountered explosions from propane tanks as they entered the backlot.

County fire captain Frank Reynoso said the cause of the fire is still unknown. "It will be a while before we have it under control," Reynoso said.

The 2008 MTV Movie Awards, which are scheduled to be broadcast live from the studio theme park Sunday afternoon, will go on as planned, according to an MTV representative. The theme park's opening time has been moved back to noon local time, said a Los Angeles city councilman.