Thousands of anti-government protesters have set up blockades at several major intersections in Bangkok as they seek to cripple Thailand's capital.
The protests step up pressure on Prime Minister Yingluck Shinawatra.
Police and soldiers are keeping watch as parts of the city of about 12 million people have ground to a halt.
There are no signs that the government is preparing to resist the protesters with force.
The upheaval is the latest chapter in an eight-year conflict pitting Bangkok's middle class and royalist establishment against the mostly poorer, rural supporters of Ms Yingluck and her exiled brother, billionaire former prime minister Thaksin Shinawatra.
Mr Thaksin was ousted by the military in 2006 and sentenced to jail in absentia for abuse of power in 2008.
Eight people, including two police officers, have been killed and scores wounded in violence between protesters, police and government supporters since the campaign against Ms Yingluck's government started in November.
Shootings were reported overnight near a government administrative complex that protesters began to blockade and at the headquarters of the opposition Democrat Party.
Although city trains and river ferries are still operating, protesters set up barricades and encampments at seven critical road intersections.
Ms Yingluck has invited the election commission and protest leaders to a meeting to discuss a snap election, which was called for 2 February.
With a commanding majority in parliament, it is likely that Ms Yingluck's Puea Thai Party will win.
Protest leader Suthep Thaugsuba has rejected the poll and the election commission has said the vote could be postponed to 4 May.