Fires broke out at a major shopping centre, the Thai stock exchange and other locations in Bangkok after an army offensive that shut down a protest camp in the capital, a fire official said.
Blazes were reported at Central World, one of South-East Asia's largest shopping centres, as well as the Stock Exchange of Thailand, a branch of an electricity company, a television station and a bank, the official said.
The government announced a night-time curfew to deal with any "rogue protesters" who ignore a call by leaders of the anti-government Red Shirt movement to end their weeks-long rally in the heart of the capital.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Officials have ordered rioters to stop looting and committing arson, or face 'decisive action'.
The Thai government has also imposed 'special programming' on television stations while the crisis unfolds.
Protesters unhappy at surrender
The causes of the blazes were not clear but there were local media reports that some hardcore anti-government protesters had lit fires because they were unhappy with the Red Shirt leaders' decision to surrender.
Protest leaders surrendered on Wednesday and told supporters to go home after a deadly army assault on their fortified encampment.
A police spokesman said crack officers had been deployed with authorisation to shoot on sight anybody looting, committing arson or inciting unrest.
Bloggers are warning the unrest is not contained to Bangkok, with reports of violence in other Thai cities.
