At least nine people, including foreigners, have been killed and 48 injured in the explosions at the luxury hotels in the Indonesian capital. There are no reports that any British people have been killed.
The first two blasts, in Jakarta's central business district, occurred at about 0730 (0030 GMT). Reuters quoted police as saying another, unexploded, bomb had also been found at the JW Marriott.
"I heard two sounds like 'boom, boom' coming from the Marriott and the Ritz-Carlton. Then I saw people running out," security guard Eko Susanto told AFP.
Latest reports as that a second unexploded bomb has been found at one of the hotels.
The Marriott Hotel was the target of a bomb attack in August 2003 in which 13 people were killed.
Video from Sky News
** Twitter was apparently the first to break the story. First at the scene was user Daniel Tumiwa - who's first Tweet read: Bom @ marriot and ritz Carlton kuningan jakarta.