The financial district of Manama was deserted, shops and malls were shuttered and Sunni and Shiite vigilantes armed with metal pipes and clubs were in the streets after hundreds of troops rolled into Bahrain from Saudi Arabia.
State television interrupted normal programming to announce the state of emergency in the strategic Gulf state, which is home to the US Fifth Fleet and major international banks and finance institutions.
"Due to the ongoing circumstances in Bahrain ... King Hamad has announced a state of national emergency as of Tuesday for three months," it said.
Armoured troops from Saudi Arabia and the United Arab Emirates had earlier rolled across the causeway from Saudi's Eastern Province to help Manama deal with pro-democracy protests which have shaken the kingdom for the past month.
UPDATE: BBC Radio 4 6pm (GMT) News: Al Beeb are now pretending this is a battle for democracy and presenting it as such.