The boat was ferrying passengers when its engine exploded near the Wat Thepleela Pier in the city's eastern outskirts, throwing many passengers in the canal that also serves as a major waterway.
The cause of the explosion was believed to be a fuel leak on board, local police commander Sarayuth Junnawat said. The severity or the nature of the injuries was not immediately clear, however, at least two passengers were reported to be badly scalded in the accident.
Commuter boats is a popular mode of transport in the city, that was once called the 'Venice of the East' because of the numerous canals criss-crossing the city. Many prefer it to avoid the notorious traffic jams on the roads.
The boat was travelling on the Saen Saeb canal, which runs through the heart of the city and connects to its main Chao Praya river.