Police use tear gas to disperse protesters in Thailand.

Tensions are rising, with thousands swarming government buildings on Sunday, trying to force a government shutdown.

One group tried to dismantle road blocks at the Government House, where the prime minister holds office.

The protesters threw back tear gas canisters in response to police.

Another group approached the Metropolitan Police department, and were also dispersed.

Smoke filled the streets.

Security was beefed up around the capital, as the government anticipated a big push from protesters on Sunday.

The protesters are demanding that Prime Minister Yingluck Shinawatra step down from office, accusing her of empowering her exiled brother Thaksin.

These protests are the biggest since 2010. Back then, it was Thaksin's supporters who were challenging the government.

Those demonstrations paralysed the Thai capital, and ended in a deadly military crackdown.