MONTROSE, Colo. – Investigators probing what caused a jet to crash during takeoff want to know whether it was de-iced before it went down, killing NBC sports executive Dick Ebersol’s youngest son and two other people, a federal official said Tuesday. They have not ruled out other possible factors.

“We do want to look at de-icing because of the weather conditions but we’re not going to just focus on one possibility,” Ellen Engleman Connors, chairman of the National Transportation Safety Board, told CBS’ “The Early Show.”

The plane carrying Ebersol and two of his sons crashed Sunday while taking off from the airport outside this small town 185 miles southwest of Denver. A snowstorm had moved through the area and there was light snow and fog at the time of takeoff.

Digging through the charred wreckage, investigators on Monday found what is believed to be the body of 14-year-old Edward Ebersol, youngest son of Ebersol, 57, and his wife, “Kate and Allie” star Susan Saint James.

The couple’s oldest son, Charles, and the plane’s co-pilot remain hospitalized and are expected to recover. Saint James and the middle Ebersol son, 18-year-old Willie, were not on the flight.

The pilot, 50-year-old Luis Alberto Polanco Espaillat of the Dominican Republic, and flight attendant Warren T. Richardson III, 36, of Coral Gables, Fla., were also killed. The co-pilot was in critical condition at a burn unit in Denver.

The plane’s voice recorder was recovered Monday. The jet did not have a flight data recorder.

“I had two major concerns when I got here,” said Arnold Scott, the NTSB’s lead investigator. “The first was to recover the sixth occupant and the second was to recover the cockpit voice recorder. We accomplished those things and now we’ll get into the intricate details of the investigation.”

Connors said that among the factors to be studied are “structural failure, fuel imbalance, engine failure, was there a problem with air speed, human factors” and weather. Investigators will interview Ebersol when doctors allow it, she said.

Steve McLaughlin of MTJ Air Services, which de-ices private planes at the airport, said his company did not de-ice Ebersol’s plane before it took off. Airport Manager Scott Brownlee said he did not know whether the plane had been de-iced.

Witnesses said it appeared the plane, a CL-601 Challenger, never got off the ground, and Scott said one of the survivors said it felt as if the plane was sliding off the runway during takeoff.

Doug Percival heard the crash and ran from the office of the towing company where he works. He said Charles pleaded for him to rescue his kid brother, and Dick Ebersol sat nearby on the snowy ground amid the billowing smoke, numbly rocking back and forth.

“You could tell he was in shock. Both of them had been ripped out of their shoes,” Percival said.

Percival said he was going to crawl through a hole in the plane to look for survivors but turned around because of smoke. He said leaking jet fuel soon exploded “like Roman candles.”

Gary Ellis was teaching Sunday school at a Baptist Church near the airport when he heard a loud “poof.”

“It came to a rest, and a moment or two later it exploded into a huge fireball,” Ellis said. “It was burning as it came down the runway.”

With light snow falling Monday morning, crews began picking through the blackened pile of twisted metal and a 6-foot-high shard of warped fuselage. Two engines lay on the ground near the tail section and cows from a nearby pen looked on as a backhoe was brought in to dig under the wreckage.

Investigators finally pulled out the body just before dark, using another tractor to lift up the wreckage before covering the site with a gray tarp as they wrapped up for the night.

“I’m not going to discuss the condition of the body out of respect for the family,” coroner Mark Young said. “May God be with his soul.”

The Ebersols were flying home from California after the University of Notre Dame played Southern California in a football game on Saturday. Charles is a senior at Notre Dame and Willie is a freshman at USC.

The plane stopped in Colorado to drop off Saint James, then was supposed to head Indiana to drop Charles off at Notre Dame.