Troops in the West African state of Niger have staged a coup seizing President Mamadou Tandja and government ministers.
State television says the country's borders are closed and a curfew is in force. The constitution has been suspended.
The BBC reports normal programming on State radio has been replaced by martial music.
Niger is an important source of uranium and has recently received substantial investment from China and France.
The BBC reports tanks are on the streets and official buildings have been fired on.
Fighting broke out around the presidential palace at about 1300 (1200 GMT) on Thursday.
A government source said Mr Tandja was captured while he was chairing a weekly cabinet meeting.
Niger has experienced long periods of military rule since independence from France in 1960.
Mr Tandja was first voted into office in 1999 and was returned to power in an election in 2004.
The former army officer was widely criticised when he changed the constitution in August to allow him to stand for a third term.