A huge car bomb exploded outside the Danish Embassy in the Pakistani capital on Monday, killing at least six people and wounding dozens more, officials and witnesses said. The blast echoed through Islamabad and left a crater over three feet deep in the road in front of the main gate to the embassy. Glass, fallen masonry and dozens of wrecked vehicles littered the area. People, some bloodied, ran helter-skelter in a state of panic. A perimeter wall of the embassy collapsed and its metal gate was blown inward, but the embassy building itself remained standing though its windows were shattered. There was no immediate claim of responsibility, but al-Qaida No. 2 Ayman al-Zawahri recently called for attacks on Danish targets in response to the publication of caricatures in Danish newspapers depicting the Prophet Muhammad. The blast also came amid efforts by Pakistan's new government to strike peace deals with militants in its regions bordering Afghanistan, a pursuit eyed warily by the US. Pakistani officials condemned the blast but indicated they did not want to stop the talks. The government has insisted it is not talking to "terrorists" but rather militants willing to lay down their weapons. "There is no question of any impact of this incident on the peace process, but of course it badly harmed our image in the world," said Rehman Malik, the Interior Ministry chief. Officials said at least six people - including two policemen - were killed and 35 people were wounded in the blast, none of them foreigners. It was the second targeting of foreigners in the usually tranquil Pakistani capital in less than three months. Danish Foreign Minister Per Stig Moeller said the explosion killed a Pakistani cleaner at the embassy, seriously wounded a handyman there and injured two office workers. No Danes were reported among the victims. Moeller called the attack "totally unacceptable." "It is terrible that terrorists do this. The embassy is there to have a cooperation between the Pakistani population and Denmark, and that means they are destroying that," Moeller said. The Norwegian and Swedish governments immediately closed their embassies in Islamabad. The homes of the Dutch ambassador and the Australian defense attache, located near the Danish embassy, were damaged in the blast, but none of their staff were reported injured. The US Embassy, meanwhile, urged Americans to use extra caution when traveling through Islamabad and to avoid the blast site. Policeman Muhammad Ashraf said it appeared to be a car bomb. Someone had parked a car in front of the embassy and it exploded at around 1 p.m, he said. Kamal Shah, a senior Interior Ministry official, said the Danish Embassy promised to supply investigators with footage from its closed circuit cameras. He said it was not yet clear if it was a suicide bombing, a time bomb or one detonated by remote control. The engine of the vehicle was catapulted 100 feet. It landed in a private villa in a neighboring street. "I was with a friend passing through a nearby street then we heard a big bang," said bystander Muhammad Akhtar. "Then we saw smoke and people running in a frenzy. We shifted at least eight or nine injured to hospitals. They all have got serious injuries. They were soaked in blood." The office of a Pakistani development organization opposite the embassy was badly damaged. Its roof had partly collapsed. Anjum Masood, a field operations manager for the U.N.-funded group, Devolution Trust for Community Empowerment, said dozens of its 100 employees were wounded, mostly by flying glass. His own left hand was bandaged. He said the group had been worried about its location across from the embassy. "We tried to voice our concern that it should be moved ... We were under a lot of threat." A plume of smoke rose above the scene of the blast and sirens wailed. The Danish flag and the EU flag were blown off their staffs and had snagged onto the first floor balcony of the main embassy building. The guard house outside the embassy was badly damaged. Denmark has faced threats at its embassies following the reprinting in February by about a dozen newspapers of a cartoon that depicted Islam's Prophet Muhammad wearing a bomb-shaped turban. That and other images in a Danish paper sparked riots in the Muslim world in 2006. Ben Venzke, chief executive officer of IntelCenter, a US group that monitors al-Qaida messages, said the bombing was likely the work of the terror group or one of its affiliates. He said al-Qaida laid out an extensive justification for attacks against Danish diplomatic facilities and personnel in a video last August, and repeated its threat earlier this year. "I urge and incite every Muslim who can harm Denmark to do so in support of the Prophet, God's peace and prayers be upon him, and in defense of his honorable stature," IntelCenter quoted al-Zawahri as saying in an April 21 video. Foreign Secretary Salman Bashir pledged Pakistan would do all it could to safeguard foreign diplomatic missions. "I think the Pakistani nation feels very ashamed today on incidents such as these," he said. The Pakistani capital is regarded as one of the most secure cities in the country but embassies and aid agencies are likely to consider an evacuation of all but nonessential staff after the bombing. In April, embassy personnel from the Netherlands shifted to a luxury hotel in Islamabad due to concerns following the release of a film critical of the Quran, the Islamic holy book, by a Dutch parliament member. Monday's attack follows a bombing in March at a restaurant in Islamabad that killed a Turkish aid worker and wounded at least 12 others including at least four FBI personnel. Taliban and al-Qaida-linked militants have launched a wave of bombings in Pakistan over the past year, mostly targeting security forces. But there has been a relative lull in violence since a new civilian government took power two months ago and began the peace talks. The United States has expressed concerns that the peace deals will simply give the militants time to regroup and intensify attacks on US and other foreign forces inside Afghanistan. Pakistani Muslims have staged peaceful protests this year over the Muhammad cartoons, including about 300 people in the central city of Multan on Monday. In April, Denmark briefly evacuated staff from its embassies in Algeria and Afghanistan because of terror threats related to the Muhammad drawings.