'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.

Witness Intan told TV One one of the explosions wrecked the lobby of the Plaza Mutiara building.

'I was having breakfast on level 16, I heard an explosion and went down to the first floor and it was a mess. I saw foreigners all bloody, about three to five of them, badly wounded,' she said.

'I saw some people being carried into a Mercedes. There was a lot of them in there, they were having trouble closing the doors,' a witness, who gave her name as Mery, told ElShinta.

Alex Asmasubrata, who was jogging by the hotels, said he first heard a loud explosion at the Marriott. Five minutes later, a bomb followed at the Ritz. He saw four bodies inside the Marriott, including one with its stomach blown out.

'Some windows of the Ritz-Carlton building have been shattered, mostly on the lower section. I?m looking at it from my office,' said Myra Junor, who works at a nearby building.

Lydia Ruddy, a witness who lives in the area, told Reuters she could see debris everywhere.

She said she heard an explosion and saw smoke coming from the Marriott, followed five minutes later by another explosion at the Ritz-Carlton hotel, which is in the same area.

An Australian man told local Radio 2UE his son had been hurt at the Marriott and was being taken to hospital.