Two suspects involved in Tuesday's bombings in downtown Bangkok were charged with criminal offenses instead of terrorist acts on Wednesday as Thai authorities tries to play down the incident.

Charges have been filed against two Iranian men identified as Saeid Moradi and Mohammad Hazaei for possessing explosive materials, harming and attempting to kill others, Thailand's Foreign Minister Surapong Tovichakchaikul said.

"At the moment, there is no evidence linking this incident to terrorism," he added.

Four foreigners fled after an explosion in a rented house in Bangkok. Saeid Moradi threw a bomb at a taxi after the driver refused to take him, injuring the driver and three pedestrians. Then he threw a bomb at a police car but it bounced back and blew up in front of him, according to police accounts.

Saeid Moradi lost his legs in the explosion and is being treated in a local hospital.

The other suspect Mohammad Hazaei, was taken into custody at Suvarnabhumi Airport while attempting to board a plane to Malaysia. He denied involvement in the explosions.

Two more suspects, including a woman, were still at large. Deputy police chief Pol Gen Pansiri Prapawat said one suspect identified as Masoud Sedaghatzadeh left Bangkok for Kuala Lumpur on Tuesday afternoon.

The suspects could be using fake documents and the Thai authorities were checking their identities with the Iranian embassy, Surapong said.

Police found explosive devices in the rented house. "In my personal view, the first explosion occurred when the suspects were trying to assemble bombs," Thailand's Defense Minister Sukumpol Suwanatat said.

Wichean Potephosree, secretary general of National Security Council, said the explosive devices found at the rented house were not for terrorism or sabotage because they are not powerful enough to cause large-scale destruction.

The explosives were most likely intended for use in attacking individuals. But it was not clear who or which organization was the target, he added.

The Thai government and business community worry that the blasts would damage tourism, a pillar industry of Thailand. Thai Prime Minister Yingluck Shinawatra said she ordered the police to step up security at tourist attractions.

Some countries have issued travel warning to Thailand, including the United States, Britain and Japan. In a warning issued Tuesday after the blasts, Britain suggested its citizens use caution in Bangkok, Chiang Mai, Chiang Rai, Khon Kaen, Ubon Ratchathani and Udon Thani.