Witnesses, including passersby who helped carry victims to ambulances, said the office building burned for an hour and that several bodies lay on the street in front. The blast, which occurred around 5:45 p.m., could be heard at least one mile away.
The bomb appeared to have exploded inside a Toyota Corolla sedan, a common model here. The car's charred wreck lay just outside the building that housed DynCorp, but it was not clear whether a driver had been inside. One purported Taliban spokesman said the attack had been a suicide bombing. Later, however, a Taliban spokesman told the Reuters news agency that the car bomb had been detonated remotely.
An Afghan police officer and an American security guard try to maintain order after a bomb exploded outside the Kabul office of DynCorp Inc.
(Ahmad Masood -- Reuters)
Video Report: An explosion tore through the office of an American defense contractor in the Afghan capital Sunday, killing as many as six.
Police wielding riot sticks kept crowds of bystanders from the bomb site, while merchants on a half-dozen surrounding blocks swept up piles of jagged glass. Many windows and the entire glass lobby of a new 10-story office building were shattered.
"I heard a very, very loud sound and saw all my windows breaking. Then someone came in and asked for help. He was bleeding from his head and hands and leg," said Mauladat, 45, who owns a pharmacy one block from the bombing.
The Shar-I-Nau district, where the bomb exploded, is one of the most affluent commercial areas of Kabul. It houses international aid agency offices, inns and apartments, restaurants that cater to foreigners, Internet cafes, carpet shops, several embassies, doctors' offices and travel agencies.
"This work is my responsibility. The enemies of Afghanistan do not want it to be reconstructed, but the work will continue," vowed Mahmad Rassool, construction supervisor for the Kabul City Center office building. The new lobby gaped open, and thousands of pieces of thick green glass littered the sidewalk around it.
The afternoon school bombing in Paktia occurred in a relatively remote part of the country, and few people in Kabul were aware it had happened when the evening blast shook the capital. Officials in Paktia said one adult and eight children were killed, and they speculated that the school was targeted because it received foreign financial aid.
Attacks by Islamic extremists have increased recently as Afghanistan's historic election approaches. Vehicles carrying election workers have been bombed, and 12 Afghan election workers have been killed in rural areas.
The Taliban, a radical armed Muslim movement, seized power in most of Afghanistan in 1996 but was driven from power by a U.S.-led military intervention in 2001. U.S. troops have been hunting down remnants of the Taliban ever since, but its guerrilla fighters have regrouped and staged dozens of attacks on aid workers, U.N. offices and Afghan government facilities.
Almost all the attacks have occurred in rural areas, and few have taken place in the capital, which is patrolled by more than 4,000 peacekeeping troops provided by NATO. Western governments have pledged to step up the number of troops in October to help protect the elections.
Staff writer Martin Weil in Washington contributed to this report.