Several bombs exploded in downtown Bangkok late on Sunday, killing at least two and injuring many people, a police official said.
Police said that one roadside bomb exploded at around 6:30 pm local time (1130 GMT) along Sukhumvit road, causing injuries to several by-passers. Several vehicles around were also damaged.
Almost at the same time, in the explosion at the Klong Toei area near the Na Ranong intersection, a bomb hidden in a trash can near a Chinese spirit shrine exploded and injured two by-passers.
It also caused a secondary explosion to a number of cooking gas cylinders lying nearby.
One person was died at the Big C supermarket, Sapan Kwai branch, where a man was seen dropping a grenade from a pedestrian bridge, police said.
At least 20 people were injured at the Victory Monument when a powerful bomb went off near a bus station. Reports said one was killed on the spot.
Authorities have ordered all shoppers to evacuate the mall, one of Bangkok's largest, and all shops to close down for business.
Government spokesman Yongyuth Malyalarp urged the public to remain calm, adding that police officers were instructed to stay on high alert, including areas where high concentration of people is expected on the New Year's eve.
"Police reinforcement have been sent to various areas in the city. We urge the public to remain calm and continue with the celebration," Yongyuth said.