TORONTO - Toronto's airport was under "red alert" because of the threat of lightning when an Air France jetliner landed in a fierce rainstorm despite having enough fuel to reach another airport - a decision that was made by the pilot, airport authorities said Wednesday.

Investigators searching the wreckage of the Airbus A340 found the flight data and voice recorders - the so-called "black boxes," said Steve Shaw, spokesman for the Greater Toronto Airports Authority. Officials hope the recorders will provide clues to what caused the aircraft to skid off a runway Tuesday at Lester Pearson International Airport

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Brian Lackey, vice president of operations for the Greater Toronto Airport Authority, said Wednesday the jetliner had enough fuel to divert to Montreal or another airport where the weather was better, but "that's the pilot's decision."

The airport was under a "red alert," which does not prevent planes from landing or taking off.

Real Levasseur, lead investigator for Canada's Transportation Safety Board, said the decision to land during a "red alert" would be investigated.

He emphasized that wind shear likely wasn't a factor in the crash because that usually would only affect aircraft in flight. He also doubted lightning played a role.

Levasseur said the black boxes were in relatively good condition. "There is some fire damage to them, but we should be able to recover the information."

Lackey said airport workers were struck by the severity of the storm. "As we were looking out the window we were commenting that storm was extremely severe," he said. "Normally if there are thunderstorms in the area, a pilot may decide to circle until it's safe to land."