Early findings show the failure occurred where the engine was under the highest pressure, though there was no immediate indication of what caused it or the fire that forced 170 people to evacuate Tuesday at McCarran International Airport as smoke poured from the aircraft.
"You really don't see catastrophic or uncontained engine failure like this very often," said John Cox, an aviation safety consultant who spent 23 years as a U.S. Airways pilot. He said the failure indicates parts sliced through the engine casing.
The National Transportation Safety Board said there was damage to the armored shell around the left engine's high-pressure compressor, and several 7- to 8-inch fragments of the compressor were found on the tarmac.
No one was seriously injured when British Airways Flight 2276 screeched to a halt and the 157 passengers and 13 crew members escaped down evacuation slides as firefighters doused flames spewing from the engine beneath the wing of the Boeing 777.
The pilot who halted the takeoff and calmly called "mayday, mayday" said he will retire one flight shy of the day he had planned to hang up his wings.
Chris Henkey of Padworth, England, told NBC News he'd never had such a close call in a 42-year career, and he's "finished flying." He won't captain what was to be his final flight to Barbados, where he intended to vacation with his daughter.
Investigators planned to interview Henkey and two senior first officers with 18 and 10 years of experience.
Henkey, 63, was hailed by fire officials and airline observers for a flawless reaction and evacuation, though he deflected praise, saying the entire crew helped. The whole ordeal lasted about five minutes. Engine fires are unusual but not unheard-of.
In July, a Southwest Airlines flight evacuated at Midway International Airport in Chicago when one engine caught fire on takeoff.
In June 2006, an American Airlines jet engine exploded during testing at a maintenance area at Los Angeles International Airport, launching parts into the body of the plane and as far as half a mile away.
No one was injured in either incident. Both jets had different engines than the British Airways plane.
NTSB and Federal Aviation Administration investigators, along with teams from Boeing and engine manufacturer General Electric, were examining the aircraft before removing the damaged engine for a thorough analysis.
The flight data and cockpit voice recorder "black boxes" and a quick access recorder arrived at an NTSB laboratory, said Eric Weiss, an agency spokesman.
Investigators in Las Vegas were expected to look at fuel lines, maintenance records and other factors.
Don Knutson, an aircraft accident investigator in Wichita, Kansas, said mechanical failure, parts fatigue or the ingestion of debris all could have created the failure.
"Jet engines suck, squeeze, burn, turn and blow," he said. "That creates the energy to propel the jet forward. If something fails during intake, it could lead to compression failure. But that in itself may not cause a fire."
The damaged components came from the engine core, which spins at ultra-high speeds adjacent to the engine combustion chamber.
The NTSB statement didn't address possible causes of the fire, or whether a fuel line might have broken.
But John Goglia, an independent aviation safety expert and former NTSB member, said it was likely flames erupted when a broken compressor blade damaged the combustion chamber awash with fuel during acceleration.
Goglia discounted passenger accounts of an explosion, saying the release of pressure would create noise but not necessarily an explosion.
He and Cox said a breach in the Kevlar-reinforced engine casing could have crippled the effectiveness of a chemical system to snuff out an engine fire in flight.
"Halon breaks down the chemistry of the fire and smothers the fire," Cox said. "When you have an open system where the casing is not intact, halon can't do its job."
Clark County Fire Chief Greg Cassell said he couldn't tell if a fire suppression system had been activated.
British Airways said the plane arrived from London Gatwick on schedule at 1:25 p.m. Tuesday. It initiated takeoff less than three hours later.
The large plane with two GE90 engines was built in 1998 and was registered to British Airways a year later. By the end of 2013, it had flown 76,618 hours, according to the British Civil Aviation Authority. GE90 engines are used in most Boeing 777s.
Aircraft records compiled by Flightglobal of England showed the engine underwent a heavy maintenance check and inspection in December 2005, which Goglia said was probably within the recommended service schedule.
He said it was unlikely the failure stemmed from a malfunction cited in a 2013 FAA airworthiness directive related to GE90 engines capable of greater thrust than the one on the British Airways jet.
The airline said all passengers were offered flights to London on Wednesday and most had taken them.
(Ken Ritter and Sally Ho - Associated Press)