Suicide bombers who checked in as guests smuggled explosives into American luxury hotels J.W. Marriott and Ritz-Carlton in Indonesia's capital and set off a pair of heavy blasts that killed eight people and wounded more than 50, investigators said Friday. The near-simultaneous bombings ended a four-year lull in terror attacks in the world's most populous Muslim nation. At least 18 foreigners were among the dead and wounded. According to police, the casualties included citizens of Australia, Canada, Hong Kong, India, Indonesia, Italy, the Netherlands, Norway, South Korea the US and Britain. Tim Mackay, president director of cement maker PT Holcim Indonesia, was among those killed, the company said. The blasts at the hotels, located side-by-side in an upscale business district in Jakarta, 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 bodies being shuttled away in police trucks. Jakarta police chief Maj. Gen. Wahyono said two suicide bombers carried out the attacks at the hotels. The suspects of the Marriott bombing stayed on the 18th floor, where un-detonated explosives were found after Friday's twin explosions. “There were several perpetrators,” he told reporters. “They were disguised as guests and stayed in room 1808.” 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.” 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) and that “high explosives were used.” A visibly upset President Susilo Bambang Yudhoyono, re-elected this month on the back of improved security and a healthier economy, told a news conference the bombings were the act of a terrorist group bent on damaging the country. “I am sure most of us are deeply concerned, feel very sorry and are crying silently, like the way I am feeling,” he said, adding the perpetrators were “laughing and cheering with anger and hatred.” “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. – AgenciesJemaah Islamiah suspectedJust a day before Friday's deadly strike, an Australian think tank, the Strategic Policy Institute, predicted the Southeast Asian terrorist group Jemaah Islamiyah (JI) was poised to strike again. A paper released Thursday said tensions in the group's leadership and the release of former members from prison “raise the possibility that splinter factions might now seek to re-energize the movement through violent attacks.” The network is blamed for past attacks in Indonesia, including a 2003 bombing at the Marriott when 12 people died. There has been a massive crackdown in recent years by anti-terrorist officials in Indonesia, a predominantly Muslim nation of 235 million, but terrorism analyst Rohan Gunaratna said the JI was “still a very capable terrorist organization.” Police have detained most of the key figures in the Indonesia-based JI and rounded up hundreds of other sympathizers and lesser figures. Authorities in neighboring Malaysia, where the group also has roots, said they were stepping up security at government buildings, shopping malls and hotels.