Thailand's military has announced it is taking control of the government and has suspended the constitution.
In a TV statement, army chief Gen Prayuth Chan-ocha vowed to restore order and enact political reforms.
The cabinet has been told to report to the military, TV broadcasting is suspended and political gatherings are banned. A nationwide curfew will operate from 22:00 to 05:00 local time.
The coup follows months of political turmoil in Thailand.
On Tuesday the army imposed martial law. Talks were then held between the main political factions, but the army announced the coup on Thursday.
Key political figures, including opposition protest leader Suthep Thaugsuban and pro-government protest leader Jatuporn Prompan, were taken away from the talks venue after troops sealed off the area.
Troops fired into the air to disperse a pro-government protest camp on the outskirts of Bangkok but there are no reports of major violence.
The broadcast media have been told to suspend all normal programming.