At least 20 people are now known to have died in clashes between anti-government protesters and troops in the Thai capital, Bangkok.
Soldiers and police opened fire with tear gas and rubber bullets as they advanced in an operation to retake areas of the city from thousands of demonstrators. The protesters fought back with guns, grenades and petrol bombs.
The BBC reports a government spokesman has denied reports that live rounds were fired.
At least four soldiers were among the dead, and a cameraman working for Reuters also died in the clashes, the news agency confirmed.
More than 800 people were wounded in the fighting near the Phan Fah bridge and Rajdumnoen Road in Bangkok's old quarter.
After hours of violence, an army spokesman said troops would pull back in the old quarter as the riot spread into Khao San Road, an area popular with back-packing tourists.
Reports from Bangkok on Sunday morning said the city of 15 million appeared to be calm as an unofficial truce took hold.
In the northern cities of Chiang Mai and Udon Thani, meanwhile, hundreds of "Red-Shirt" protesters are reported to have forced their way into government offices.
The "Red Shirt" protesters, many of whom are sympathisers of ousted leader Thaksin Shinawatra, want Prime Minister Abhisit Vejjajiva to resign and call elections, saying his government is illegitimate. They began their latest campaign on 12 March.
The Ministry of Foreign Affairs and Trade has updated its travel advice for New Zealanders in Thailand.
Foreign Affairs is advising that there is some risk to security in Bangkok and elsewhere in Thailand, due to the uncertain political situation.
A spokesperson says more detailed information on the areas of unrest has been added to the advisory, which has been emailed to the 350 New Zealanders in Thailand registered with the ministry.
MFAT says it's continuing to monitor the situation closely, and anyone travelling to Thailand should have comprehensive travel and medical insurance.
New Zealanders are being advised to register their travel details with the Ministry before they go.