Fresh gunfire broke out on Saturday morning in an area where anti-government protesters and army troops continued to face off after clashes on Friday left 16 dead.
It was not clear which side had fired.
Soldiers ran to take positions after an explosion near the Suan Lum Night Bazaar, a market and dining area normally popular with tourists.
Tyres, apparently set alight by the "Red Shirt" protesters, were burning before the shooting erupted.
Police said hundreds of demonstrators had remained in that area after a government operation Friday aimed at clearing the protesters from one area near their vast encampment, which is fortified with bamboo stakes and tyres.