- A woman whose car was hit says the debris was "so hot you couldn't even touch it"
- Police note witness reports of smoke and possible debris coming off of an airplane
- Several vehicles were damaged by mysterious debris seemingly from the sky, police say
- An Air Canada spokesman says there's "no confirmation" yet anything came from its plane
Canadian authorities are investigating reports that debris fell Monday from a troubled airliner and caused damage to vehicles in southern Ontario.
The incident centers on Air Canada Flight 001, which took off from Toronto at 2:10 p.m. ET, destined for Tokyo's Narita Airport, with 318 passengers and 16 crew members aboard.
One of the Boeing 777 aircraft's engines shut down after takeoff, prompting the flight crew to follow "standard procedure" and return to Toronto Pearson International Airport, said Air Canada spokesman Peter Fitzpatrick.
The crew requested an emergency landing, which Fitzpatrick said was standard because it gives certain planes first priority, though he also noted the aircraft involved is designed to run on a single engine if necessary.
The plane landed normally, and passengers returned to the gate, according to Fitzpatrick. Constable George Tudos, spokesman for police in the regional municipality of Peel, said the aircraft returned to Toronto's airport at 3:53 p.m.
Yet more than an hour before that, around 2:30 p.m., people began reporting seeing smoke, and one spotted what may have been debris coming from a large airliner, according to the spokesman.
Peel Regional Police ended up receiving several calls from people reporting vehicles had been damaged by things that plunged from the sky, said Tudos. As of about 4:30 p.m., three to five such vehicles were being investigated for damage.
Sarabjit Sandhu told CNN affiliate CP24 that she and her husband had just gotten gas at a Petro-Canada station in Mississauga when they "heard a big noise, a bump, like boom."
"The first thing I said (was), 'Oh my God, what is this?' " Sandhu said.
A number of vehicles around the parking lot were damaged, including a Nissan Altima with its back window shattered to pieces while its owner was inside the gas station's convenience store.
Pieces of gray, heavy material littered the scene, according to CP24.
"It was so hot you couldn't even touch it," Sandhu said of the material.
No injuries have been reported on the plane or on the ground, added the spokesman.
Fitzpatrick, the Air Canada spokesman, noted around 5 p.m. that there had been "no confirmation at this time" that debris had fallen from his company's plane.
"There will be a full investigation into this incident, as there always is, and that will determine what happened," said Fitzpatrick.
Tudos, the Peel police spokesman, said officials from the national transportation agency Transport Canada are investigating.
"Transport Canada will follow up with the company to ensure compliance with safety regulations," agency spokesman Kelly James told CNN on Monday by e-mail. "The department will not hesitate to take immediate action if safety issues are identified."