Visitors to Ruskin Park in London said the two-engine helicopter surprised them when it landed among the joggers and dog walkers about 7 p.m. Tuesday, the Daily Telegraph reported.
"When I first heard it I thought there was something wrong with my car," a witness told the Telegraph. "It was only when I pulled my car over that I realized there was a Chinook following me down the street. I got out and watched it plonk itself down among the runners and dog walkers.
"There were a lot of people on the ground nearby -- it didn't seem safe at all," the witness said.
The witness said the helicopter was "blowing over a couple of dog walkers" while it was in the park.
A Royal Air Force spokesman said the landing was a routine training exercise.
"A RAF Chinook helicopter conducted a pre-planned, landing at Ruskin Park in London this evening while on a training flight," the spokesman said. "The park is a designated Helicopter Landing Site for Kings College Hospital and the RAF was granted permission to land by Kings College. There was no danger to the public at any point."