- "There were flames, and there was lots of black smoke," an eyewitness says
- Emergency services pulled several people from the water
- All 28 passengers and two crew members are accounted for, police say
- The boat operator has stopped river tours as authorities investigate
People had to leap into the River Thames on Sunday after the amphibious tour boat taking them around London caught fire near Parliament.
"There were flames, and there was lots of black smoke," Phil Beasley-Harling, an eyewitness, told CNN affiliate ITV. "At one point, it looked as though the boat wasn't going to survive."
Amateur video showed several passengers jumping into the water as flames and smoke billowed out from the windows at the front of the London Duck Tours boat, a bright yellow vehicle that takes sightseers around the British capital by road and river.
After reports of the fire were received late Sunday morning, firefighters, a police helicopter and paramedics rushed to the scene. Several people were pulled from the water, and the blaze was eventually extinguished.
Police said all 28 passengers and two crew members on board the vessel were safe.
No one was seriously injured, and three people treated at a London hospital for "minor smoke inhalation ailments" have all been discharged, London Duck Tours said.
Most of the people on board the boat were foreign tourists, ITV reported.
The company and the London Fire Brigade both said the cause of the blaze, which damaged one third of the vessel, was so far unknown.
River tours suspended
Borough Cmdr. Alison Newcomb of London's Metropolitan Police said that the maritime coast guard is investigating.
"At the conclusion of that investigation, I anticipate they will make a decision with regards to future tours," she told ITV.
London Duck Tours said it has stopped operating tours on the river until the reason for the fire has been established.
"Should technical or safety modifications be required to our fleet, these will be introduced prior to the service recommencing," Duck Tours said, stressing that it "operates to the highest safety standards."
"London Duck Tours operates a fully modernized fleet of nine vehicles that have been completely rebuilt and refurbished between 2002 and 2012," it said. "This includes new, purpose built hulls, new engines, computerized systems and steering equipment."
The company said it was fully cooperating with investigators and regulatory authorities.
Amphibious tour vehicles have run into trouble in the past.
In June, a duck boat sank in the British city of Liverpool. Twenty-seven people were taken to the hospital for shock and exposure after that incident.
It was the second time the Liverpool tour company, The Yellow Duckmarine, had had a problem with a vehicle -- one of them sank in March without any passengers in it.
The Yellow Duckmarine, whose passengers have included the Queen and Prince Philip, is not running any tours at the moment, according to its website. Reports said it went into administration and had its road license revoked after the June sinking.
London Duck Tours said it had higher safety standards than The Yellow Duckmarine, which it described as "a totally separate company."
In Philadelphia, two people died after a 250-foot sludge barge pushed by a tugboat overran a disabled 33-foot amphibious tour boat on the Delaware River in 2010.
The barge plunged the smaller vessel, its 35 passengers and two crew members underwater.
The amphibious boat's operator, Ride the Ducks, suspended operations in Philadelphia for about nine months after the crash.