Two people are lucky to be alive after an enormous tree limb from a swaying willow tree three storeys tall came crashing down on top of them and they were able to walk away with scratches.

Their brush with death happened at about midday Wednesday in London's Gibbons Park, just as the green space was bustling with families at the nearby pool, playground and splash pad, and others, out for a quick lunchtime jog or stroll.

Rebecca Neaves, a London mother of three, was among dozens of witnesses who reported hearing the sound of splintering wood as the tree, believed to be as old as Gibbons Park itself, suddenly lost a limb weighing thousands of pounds.

"We were hanging out just by the splash pad and having a picnic when this huge crash caught all of our attention," she said.

'Quite shaken up'

Eye witnesses describe hearing a big cracking noise before this huge tree branch split off from the trunk of a willow tree that could be as old as Gibbons Park itself. (Colin Butler/CBC News)

Neaves was among the dozens of people who rushed from the nearby splash pad and pool, some in bathing suits and bare feet, to search among the tangle of branches and leaves to see if anyone had survived the crushing fall.

"There was a couple who was sitting on the bench, right under the part that came down," she said. "They seemed okay, I think, the woman just had some scratches on her back."

The woman just had some scratches on her back. - Rebecca Neaves

The man and the woman managed to walk away from the entire ordeal, miraculously with almost no physical injuries. However, several witnesses reported the pair was "quite shaken up."

Only once the branches of the tree were cut away, was it clear just how close the two came to being crushed like eggshells underneath the century-old tree's giant limb.

Eye witnesses say the two people who were sitting on this bench, a man and a woman, were lucky enough to be able to walk away after this huge tree branch came crashing down on them in Gibbons Park on Wednesday. (Colin Butler/CBC News)

Witnesses said the man and the woman were sitting on the right side of the bench and had they been sitting further apart, one or both of them may not have survived.

"Thank God they got away," said Mike Barber, a certified arborist with Davey Tree, a company working on contract with the City of London to help clean up the mess. "As far as I know, they're alright."

"Thank God they got away." - Mike Barber, arborist

Barber said the tree may be original to the park, based on his estimate that it's 120 to 150 years old.

He also believes the willow's age, combined with rot, which was only evident once the tree split, might be to blame for the huge limb coming down.

Limbs that 'fail for no reason'

'We're going to see limbs that just fail for no reason' 0:31

Barber said he'd likely be back later in the week to remove the rest of the tree, which is now a safety hazard.

"We've lost a third of it, so the rest of it is going to come down," he said.

Barber said while they are dangerous in populated areas, willows are beautiful.