BANGKOK (REUTERS/AFP) - A small explosive was thrown from a bridge over the Chao Phraya River in central Bangkok on Tuesday, but no injuries were reported.
The incident came a day after a fatal bomb blast at a city shrine.
The unidentified man threw the explosive near the busy Sathorn Pier on the city's Chao Phraya River and it landed in a canal, said Colonel Natakit Siriwongtawan, deputy police chief of Klongsan district.
"If it did not fall in the water, then it certainly would have caused injuries," he said.
"No one was killed or injured. Police are at the scene to investigate what kind of device it was," an officer at Yanawa police station, who asked not to be named, told AFP.
He said the incident took place shortly after 1pm local time near the Saphan Taksin BTS skytrain station.
CCTV footage of the incident posted by Thairath TV showed commuters scurrying for cover over a footbridge after the device exploded in the canal, sending a large plume of water into the air.
The Yanawa police official said officers believed the device was thrown from a road and rail bridge that spans Bangkok's Chao Phraya River and overlooks the canal below.
The luxury Shangri-La hotel, the Mandarin Oriental and the French embassy are close to Saphan Taksin station.
No one claimed responsibility for the incident.
Bangkok is a city on edge after Monday night's bomb attack, described by junta chief Prayut Chan-o-cha as the "worst-ever attack" on Thailand.
At least eight foreigners are known to have died in the attack alongside five confirmed Thai deaths. The rest have yet to be identified.
More than 100 other people were injured as the blast left body parts strewn across the pavement, alongside shattered windows and mangled motorcycles.