A car bomb killed at least 11 Pakistanis outside the US consulate in Karachi yesterday, less than a day after US Defence Secretary Donald Rumsfeld left the country.
Police said the blast looked like a suicide bombing similar to the May 8 attack on a nearby hotel in Karachi that killed 11 French engineers and two Pakistanis.
The United States announced a few hours later it was closing its embassy and consulates in the strongly Muslim country, which is plagued by political violence and home to several armed Islamic groups implacably hostile to Washington.
"This is a vivid reminder of the fact that our nation is at war against terrorists who use any means at their disposal to harm Americans and others," a White House spokesman said.
A previously unknown group calling itself Al-Qanoon (The Law) claimed responsibility for the blast in a message sent to media organisations in Pakistan. It said the bomb was the start of a "jihad" against America and Pakistan's rulers. Police were investigating.
US diplomats in Pakistan said no foreigners or staff of the consulate were killed in the explosion, although one American and five Pakistani employees received minor injuries when struck by flying debris.
Twenty other people outside the consulate were wounded by the blast, which left a crater several feet deep, destroyed a guard post and damaged a concrete wall surrounding the building.
Police at first put the death toll at eight, but later said examination of body parts collected from the blast site showed another three people had been killed - all women who had been learning to drive in the area.
The explosion blew in the windows of the consulate and surrounding buildings, including the upmarket Marriott Hotel next door, destroyed around 20 cars and scattered body parts 100-200 metres down the road.
Pakistani officials said they did not rule out the involvement of a "foreign intelligence agency". Pakistan and India frequently accuse each other's intelligence services of being behind political violence inside their borders.
India condemned the bombing, as did Nato. A police official said Karachi police had received a tip-off a week ago that another suicide blast was imminent but did not have details of when or where.
It was the fourth attack this year apparently aimed at foreigners in Pakistan. As well as last month's Karachi bomb, US reporter Daniel Pearl was kidnapped and killed in January and a grenade attack on a church in Islamabad in March killed five people, including three foreigners.
Police said they believed yesterday's bomb was carried in a white Suzuki van which was driven past the consulate. The van was blown to pieces, the bonnet and engine being catapulted six or seven metres into a tree.
Labourer Mohammad Khalid said he was walking down the road when he heard the explosion.
"I felt intense heat all around me, after which I fell unconscious, only to open my eyes in the hospital," he told Reuters at the Jinnah Post-Graduate Medical Centre.
Kario, a cyclist who suffered serious injuries, said he remembered smelling smoke before losing consciousness. "I felt like a mountain had fallen on me," he said.
"Of course it's a backlash," said Hamid Haroon, publisher of Pakistan's Dawn newspaper, in a reference to Islamic radicals who oppose Pakistan's support for US-led military action in Afghanistan.
Pakistani President Pervez Musharraf abandoned his former Taliban allies in Afghanistan and became a key US ally after September 11, a move that sparked violent reaction from Islamic radicals at home.
Militant groups were further angered when Musharraf launched a crackdown on them in January. That followed a bloody attack on the Indian parliament, blamed by New Delhi on Pakistan-based militants, which took the two countries to the brink of war.
Several attacks, either in India or Pakistan, have been apparently timed to coincide with high-profile visits to the region by officials from Washington. Rumsfeld was visiting Pakistan on a regional tour aimed at averting war with India, and Pakistan police said they feared an attack was imminent.
India, backed by the United States, has demanded Musharraf stop Muslim militants crossing into Indian-held Kashmir to fight Indian rule in the disputed Himalayan region.
"It is a very sad and a very regrettable incident that we condemn fully," Indian Foreign Minister Jaswant Singh said in New Delhi about the Karachi bombing. "I am really grieved and unhappy that yet another terrorist activity of a suicide bomb variety has taken place in Karachi."
The Dawn's Haroon said the attack showed Pakistan was as much a victim of terrorism as anyone else, and said India and the United States should understand the problems Musharraf faced in his efforts to rein in Islamic radicals.