A powerful bomb was thrown into the Chao Phraya river beneath the Taksin bridge where ferries are operating services to passengers, but nobody was hurt.
The explosion sent water into the air over 10 metres high.
Witnesses near the bridge said hundreds of small pellets were strewn into all directions from the explosion whiich they said was a pipe bomb.
They said the bomb was very powerful because they saw water being sent into the air very high.
Fortunately nobody was injured.
EOD police are at the scene and seal off the area to find evidence.
It was not known if this second explosion had any link with the explosion at Ratchaprasong, but the explosion sent out hundreds of pellets similar to this explosion.
Another witness said the pipe bomb was thrown from the bridge but fell onto the water.