A man has been found in serious condition after he miraculously survived as a stowaway in the undercarriage of a British Airways flight from Johannesburg, and he might be on the same flight with the man who died falling out of the plane on a rooftop in West London, British police said on Friday.

A suspected stowaway was found unconscious on a flight from Johannesburg after the plane landed in London and a second man may have died falling out of the same flight, British police said Friday.

Authorities at Heathrow Airport found the man in the undercarriage of a British Airways plane after it landed Thursday morning on a flight from Johannesburg. Police say they believe they know his identity and that he is 24 but they are awaiting confirmation before they release any details.

While there is no evidence to link the two cases, police say they are looking into whether there is a connection to the body found an hour later in the west London community of Richmond, which is below the flight path.

British Airways said it is working with police in London and Johannesburg to establish the facts in this "rare case."

Experts believe roughly three-quarters of stowaways do not survive if they hide on a plane's undercarriage because of the extreme cold and lack of oxygen they experience as the plane reaches cruising altitude. Though not common, stowaways have in the past plunged to the streets of west London as the planes lowered their landing gear.

In September 2012, a 30-year old from Mozambique, Jose Matada, died after falling from the undercarriage of a Heathrow-bound flight from Angola on to a street in Mortlake, which is not far from where the body was found Thursday.

An inquest into his death suggested he had survived freezing temperatures of up to minus 60 Celsius (minus 76 Fahrenheit for most of the 12-hour flight, but he was believed to be dead or nearly dead by the time he hit the ground.

Aviation expert Chris Yates described the latest situation as unusual because of enhanced security measures at airports meant to deter terror and other attacks. However, he noted that the stowaways who survive have tended to be young people.

The Rev. Neil Summers, from the St John the Divine of Richmond church across the way from where the body was found, said he would lead prayers for the dead man.

"In one sense it's not totally surprising as it's happened before," he said. "It's very shocking when it's so close to you. We are going to say prayers for the people concerned tonight."