The injured attacker was identified as Saerb Morabi. Police are hunting for two others suspects.
An Ara-blooking man apparently went berserk on Tuesday, separately throwing bombs at a taxi and later at police in Klongton district.
However an explosive fell from his hand and exploded as he was targetting a police officer who approached him and ordered him to stop. The device mutilated the bomber’s legs.
Pol Lt Col Witthaya Poonsin, deputy commander of Klong Tan traffic police, said the foreigner, who has yet to be identified, threw the first bomb at a taxi on Soi Pridi Panomyong.
The explosive rolled under the vehicle and exploded, damaging the vehicle. The taxi driver was not injured as he was standing outside the vehicle at the time of the attack.
After the explosion, he ran after the suspect to the main road of Sukhumvit 71.
Witthaya said the man later walked to Sukhumvit 71 Road and when he spotted a police officer, he then tried to grab another bomb from his backpack and apparently tried to throw it at the policeman. The bomb slipped from his hand, fell down to the ground and shattered his legs.
He was rushed to Chulalongkorn Hospital.
Klong Tan police chief Col Sitthiparp Baiprasert said police are checking whether there are still any explosives left.
He added the man was likely an Arab. Initial police enquiries indicated that he was renting a house on Soi Pridi Phanomyong 36. There was also an explosion at the house at 2pm.
He said three foreigners were living at the house but two had fled.
Meanwhile Deputy Bangkok Governor Wallop Suwankhadee said the first explosion was only 500 metres away from Kasem Witthaya School.
Sanchai Boonsoonnern, the driver of the damaged taxi, told the Rawangpai TV programme, that the foreigner suddenly threw a bomb at his vehicle.
The bomb fell on the bonnet of his car and rolled under it before exploding.
The taxi driver was standing outside the vehicle but shouted for help and tried to run after the attacker who ran towards Sukhumvit 71.
Sanchai said the man tried to stop taxis to flee but none picked him up. Sanchai said he saw the man pulled out something from his bag and it fell on the ground and exploded.
Foreign Ministry Spokesman Thani Thongphakdee said it could not be concluded for the time being that the explosions were acts of terrorism. He added that the explosions might not be related to terrorist warning by foreign embassies, which was lifted 10 days ago.