Tour boat passengers jumped into the River Thames to escape a fire on their World War Two-era amphibious vehicle near London's Houses of Parliament on Sunday, the emergency services said.
A London Fire Brigade spokesman said up to 30 tourists were rescued from the water and from the boat after the fire broke out just before lunchtime. No one was seriously hurt.
Video footage of the scene showed flames and smoke billowing from the front of the vessel as rescuers pulled passengers wearing life jackets to safety on the nearby river bank.
"People are clearly cold, wet and in shock but they were pulled from the water really quickly," said Neil Withers, a manager at the London Fire Brigade.
"A number of people jumped into the water but they were soon rescued and fortunately at this stage it does not look like anyone has been seriously injured."
The bright yellow amphibious buses, known as Ducks, are a familiar sight in central London. They give visitors tours of the capital on land and in the Thames.
They were originally used during World War Two as landing craft and to transport soldiers and cargo in areas where the docks had been destroyed.