A bomb exploded opposite of King Power firm in Soi Rangnam in Phaya Thai district early Friday morning, injuring a man.
Police has not yet identified the injured man who was rushed to nearby Rajvithiee Hospital.
Police and rescue workers who rushed to the scene had to wait for 20 minutes before rescuing the man out of fear that there would be hidden explosives.
Police believed that the explosive was hidden in a plastic black bag in a garbage bin. The injured man was a trash collector, his three-wheeled vehicle was left parking near the bin.
Samruey Thopsak, 37, a taxi driver, said that he parked his car about 200 meters from the explosion site and he saw the flames of the explosion at a tree.
After the explosion, he alerted police.