At least 58 people were injured in Thailand's capital Bangkok after the engine on a water taxi exploded as it pulled into a pier.
Most of the injured suffered from minor burns, police said, though two passengers were said to have been seriously hurt by flying debris.
Initial reports suggested that a fuel leak was to blame.
Water taxis ply the canals around Bangkok and are a popular form of transport in the traffic-choked city.
Video of the incident posted by the Khao Sod newspaper shows the crowded boat pulling into Wat Thep Leela pier in eastern Bangkok with clouds of black smoke visible at the rear.
A group of seemingly oblivious passengers initially try to board the boat before it is rocked by an explosion.
Dozens of people are then seen leaping on to the pier to safety.
Two Myanmar nationals and one Japanese national were among those injured, the Erawan medical emergency centre said.
The boat ran on both diesel and liquefied natural gas, Khao Sod reported. The firm that runs the service is using only diesel on its boats until the results of the investigation are known, it said.
More than 100,000 people use the canal boats in Bangkok every day, according to statistics from 2012.