The hotel is in the heart of Jakarta's business district

"People were screaming, panicking," said Sodik, who was on the 27th floor of an adjacent building.

"I thought it was an earthquake," he told the Associated Press news agency.

Another eyewitness, Tarsim, was on the ninth floor of the adjacent Mutiara Plaza building when the bomb exploded.

"I saw some people injured on their face because of the broken glass. It was a nightmare," Tarsim told BBC News Online.

J Stone also emailed to say that he was working in an office about 5 km ( 3 miles) from the Marriott, but yet the bomb was "so strong that at first I thought the blast happened in the building I was in".

One of my windows was shattered by the force Madina Sar-Diarra

Those inside the hotel could only watch as the first few floors were engulfed in smoke.

"One of my windows was shattered by the force," said Madina Sar-Diarra, who lives in an apartment on the 30th floor.

"It was a panic and once downstairs, I saw several injured people, especially cooks of the restaurant, covered in blood," she told the French news agency AFP.

Jaganathan Nadeson said he looked out of his window on the 22nd floor, and saw vehicles engulfed in flames - one of which was probably the car bomb itself.

HAVE YOUR SAY If only you could see what I saw Vivek Mahtani Send your experiences

Asroni, a member of staff at the hotel, said: "I heard a big bang and I tried to get out of the building as quickly as possible."

"The smoke was getting into my lungs," he told the Associated Press news agency.

A large crowd of onlookers quickly gathered at the scene, staring at the gutted remains of the hotel lobby, and the blood and pieces of skin staining the ground.

At the forefront in their minds was why the blast had happened, and who was behind it.

Vivek Mahtani, who is staying in the Sailendra apartment connected to the Marriott, told BBC News Online: "If only you could see what I saw, then you would realise the potential that terrorists have to strike at any time ( and any) place, and zero in on what they want."