Police work at a blast site in Bangkok, Thailand, Feb. 14, 2012. Explosions on Tuesday afternoon injured five people, including one Iranian suspect, on Sukhumvit road in Bangkok, local TNN 24 news channel reported. (Xinhua/Rachen Sageamsak)

The explosion damaged public telephone booths and his bag was scattered. The police car and a pizza shop opposite the school were damaged.

The explosive device was initially believed to be hand grenades. Police later searched the rented house and found functional C-4 explosive.

The injured were sent to hospitals. Police is investigating.

Thai authorities have not yet commented whether the explosions were related to terrorism.

On January 13, the embassy of the United States warned their citizens in Thailand of the possibility of imminent terrorist attacks in busy tourist areas of Bangkok. The warning prompted other 20 countries to issued same warning for their citizens.