BANGKOK: A bomb put inside a garbage bag exploded at a street market in Thailand's capital and injured seven people, police said.

Police Col. Narongrit Promsawat said the explosion slightly injured seven people and damaged merchandise stalls at the market Sunday night. It happened in a residential area in front of a barber shop and across from Ramkhamhaeng University.

Forensic scientists said the bomb was made of nails and other materials but they have not verified what set off the explosion.

Narongrit said the area was prone to violence from school gang rivalry and a suspect might have disposed of the bomb in the trash to avoid a search by the police.

No one has been arrested.