CNN) -- Musicians DJ AM and Travis Barker should fully recover from severe burns they suffered during a fiery jet crash in South Carolina that killed four people, a doctor said Sunday.
DJ AM, left, and Travis Barker backstage at the MTV Video Music Awards on September 7.
1 of 2 DJ AM, whose real name is Adam Goldstein, and Barker, the former drummer for Blink-182, are being treated at the Joseph Still Burn Center in Augusta, Georgia, after suffering second- and third-degree burns, said Dr. Fred Mullins, the center's executive director.
Barker received burns on his torso and lower body from the jet crash late Friday. Goldstein was burned on his arm and head, Mullins said.
Though he expects a full recovery, Mullins said Barker and Goldstein could be hospitalized for weeks. Watch charred wreckage of the plane »
One witness said he saw Barker and Goldstein trying to extinguish flames on their bodies by ripping off their clothing.
"We turned to the jet to try and see if there was anything we could do, but immediately, there was nothing anyone could do," William Owens told CNN affiliate WIS in Columbia, South Carolina. "I felt ill or sick to think that these lives were snuffed out at that point."
Federal investigators have recovered the cockpit voice recorder and are also obtaining recordings of conversations between controllers in the tower and the jet's two-person crew, said National Transportation Safety Board spokeswoman Debbie Hersman.
Travis Barker, DJ AM critically injured in crash
WIS: Doctor says survivors are doing "very well"
WLTX: Cockpit voice recorders recovered
"Air traffic controllers did observe sparks from the aircraft as it was going down the runway and immediately alerted fire-rescue crews at the airport," Hersman said at a news conference Saturday evening.
Authorities don't know where the sparks originated but found "some rubber and other airplane parts on the runway," Hersman said.
The Learjet 60 was taking off from the Columbia Metropolitan Airport at 11:53 p.m. Friday when it crashed, authorities said. Barker and Goldstein had played earlier at a free outdoor concert in Columbia's Five Points district, WIS-TV said.
The plane went off the end of the 8,600-foot runway and crashed through light towers and an antenna array before crossing a road and stopping at an embankment.
"We can't tell you at this time whether the airplane was airborne," Hersman said.
Lexington County Coroner Harry O. Harman said those killed in the crash were from California. He identified them as pilot Sarah Lemmon, 31, of Anaheim Hills; co-pilot James Bland, 52, of Carlsbad; Chris Baker, 29, of Studio City; and Charles Still, 25, of Los Angeles.
Baker was Barker's assistant, and Still was his security guard, according to The Associated Press. A publicist told AP the men were Barker's close friends.
Goldstein was brought to the Augusta hospital by helicopter and Barker by ground transportation, said hospital spokeswoman Beth Frits. The hospital is about 75 miles south of Columbia.
Federal Aviation Administration spokeswoman Kathleen Bergen said the twin-engine, private jet was cleared for takeoff on a flight to Van Nuys, California, and began its takeoff a few minutes before midnight. There were no aircraft on the runway and no vehicles on the road, Bergen said.
"The weather was clear with light winds," Hersman said.
The crash closed the airport, which is Columbia's main commercial and passenger terminal, and it remained closed late Saturday night. The airport's Web site listed nine commercial airline flights canceled through 7 p.m. Saturday.
The airport will not reopen until investigators finish collecting debris from the runway and crash site, Hersman said.
The Learjet 60 was manufactured in 2006 and was powered by Pratt & Whitney 305A engines, Hersman said. The jet is owned by Inter Travel and Services Inc. and operated by Global Executive Aviation, she said.
A Web site for Global Executive Aviation lists its headquarters as Long Beach, California.
In addition to playing with Blink-182, Barker has appeared in the MTV reality show "Meet the Barkers" along with his wife at the time, former Miss USA Shanna Moakler, according to MTV's Web site.
According to DJ AM's Web site, Barker and DJ AM recently collaborated on a mixtape titled, "Fix Your Face."