The blasts at the J.W. Marriott and Ritz-Carlton hotels, located side-by-side in an upscale business district in the capital, blew out windows and scattered debris and glass across the street, kicking up a thick plume of smoke. Facades of both hotels were reduced to twisted metal. An Associated Press reporter at the scene saw bloodied bodies being shuttled away in police trucks.
President Susilo Bambang Yudhoyono said the attack was carried out by a "terrorist group" and vowed to arrest the perpetrators. He said it was too early to say if the Southeast Asian Islamic militant group Jemaah Islamiyah, blamed for past attacks in Indonesia, including a 2003 bombing at the Marriott, was responsible.
"Those who carried out this attack and those who planned it will be arrested and tried according to the law," a somber-looking Yudhoyono told a news conference.
Jakarta's police chief said several suspects in the bombing of the Marriott were staying at the hotel.
Maj. Gen. Wahyono said the suspects stayed on the 18th floor of the hotel where un-detonated explosives were found after Friday's twin explosions.
Wahyono told reporters, "There were several perpetrators. They were disguised as guests and stayed in room 1808."
He said the attacks killed 8 and wounded 50, including 18 foreigners. Earlier the security minister said nine people died, but that number was later revised by authorities.
The Marriott was hit first, followed by the blast at the Ritz two minutes later. The attacks came just two weeks after presidential vote expected to re-elect Yudhoyono who has been credited with stabilizing a nation previously wracked by militancy.
Theo Sambuaga, chairman of the parliamentary security commission, said "there are indications of suicide bombs" at the two hotels. "That is being investigated."
Local MetroTV reported that investigators suspect the attackers may have been hotel guests, who smuggled explosives past security checks. An unexploded bomb was found on the 18th floor of the Marriott after the blasts and removed by an explosives disposal team, said an investigator who declined to be named because he was not authorized to speak to the media.
But top anti-terror official Ansaad Mbai told AP it was too early to conclude suicide bombers were responsible.
Security Minister Widodo Adi Sucipto told reporters at the scene the hotel blasts happened at 7:45 a.m. and 7:47 a.m. (0045 GMT, 8:45 p.m. EDT) and that "high explosives were used."
Alex Asmasubrata, who was jogging nearby, said he walked into the Marriott before emergency services arrived and "there were bodies on the ground, one of them had no stomach," he said. "It was terrible."
Anti-terror forces with automatic weapons were rushed to the site, and authorities blocked access to the hotels in a district also home to foreign embassies.
"This destroys our conducive situation," Sucipto said, referring to the nearly four years since a major terrorist attack in Indonesia — a triple suicide bombing at restaurants at the resort island of Bali that killed 20 people.
'This is a blow to us'
The security minister and police said a New Zealander was among those killed, and that 17 other foreigners were among the wounded, including nationals from Australia, Canada, Hong Kong, India, Italy, the Netherlands, Norway, South Korea the U.S. and Britain.
The dead New Zealander was identified by his employer as Timothy David Mackay, 62, who worked for cement products manufacturer PT Holcim Indonesia. He was reportedly attending a business meeting at the Marriott Hotel when the explosions occurred.
Noel Clay, a US State Department spokesman in Washington, said that several American citizens were among the injured.
Earlier, South Jakarta police Col. Firman Bundi said that four foreigners were killed, but gave no details.
Manchester United football team canceled a planned visit to Indonesia. The team had been scheduled to stay at the Ritz on Saturday and Sunday nights for a friendly match against the Indonesian All Stars, the Indonesian Football association said.
There was no immediate claim of responsibility for the attacks, but terrorism analyst Rohan Gunaratna said the likely perpetrators were from the al-Qaida-linked Jemaah Islamiyah.
"The only group with the intention and capability to mount attacks upon Western targets in Jemaah Islamiyah. I have no doubt Jemaah Islamiyah was responsible for this attack," he said.
There has been a massive crackdown in recent years by anti-terror officials in Indonesia, a predominantly Muslim nation of 235 million, but Gunaratna said the group was "still a very capable terrorist organization."
Police have detained most of the key figures in the Indonesia-based Jemaah Islamiyah, and rounded up hundreds of other sympathizers and lesser figures.
But Gunaratna said that radical ideologues sympathetic to JI were still able to preach extremism in Indonesia, helping provide an infrastructure that could support terrorism.
Jakarta chief of police operations, Arief Wahyunadi, said the blasts were in the Ritz-Carlton's Airlangga restaurant and in the basement of the Marriott. He gave no details on what kind of bombs were used and whether they were suicide attacks.
Government spokesman Dino Patti Djalal told CNN the scene of the blasts were "eerie," when he arrived.
"The bodies I saw, some were being collected, some were on the floor," he said. "What we know, of course, is this was a coordinated attack."
When asked if Jemaah Islamiyah was behind the attack, Djalal said: "We always knew there are terrorists out there. But we've had a number of very good successes; no major attacks since the Bali bombings."
He was referring to the October 2002 bombings of two Bali nightclubs that killed some 202 people, many of them foreign tourists.
"This is a blow to us," Djalal said, but said the government would find those behind the attacks.
"The president has built his reputation on ... anti-terrorism policies," he said. "Make no mistake, he will hunt whoever is behind this."
Because of past attacks, most major hotels in Jakarta take security precautions, such as checking incoming vehicles and requiring visitors to pass through metal detectors. Still, international hotels make attractive targets, since the nature of their business requires them to be relatively open and accessible.
On Friday, Australia and New Zealand updated their travel advisories, which had already warned against unnecessary travel to Indonesia because of the risk of terrorism.
"We advise you to reconsider your need to travel to Indonesia due to the very high threat of terrorist attack," the Australian Foreign Ministry said on its Web site. Those in Indonesia were warned to exercise "extreme caution."
New Zealand urged its citizens in Indonesia to keep a low profile.
Britain also updated its travel warning, though it did not raise its alert level.