The first explosions could be heard about 12:27 p.m. EDT. Five large explosions shook the city, followed by the sounds of anti-aircraft fire.
Power went off throughout the city almost immediately after the first of five thunderous blasts.
There was no indication what caused the blasts, which appeared to have been in the southwest of the city.
The southwestern part of Kabul includes the Darulaman Palace, an ancient royal residence, and the Balahisar Fort, an old Mogul style installation.
A curfew was in effect in the city, making it impossible to independently determine further details.
(CNN) -- The United States launched an attack on Afghanistan and its ruling Taliban on Sunday in retaliation for the September 11 terrorist strikes on New York and Washington.
"On my orders, the United States military has begun strikes against al Qaeda training camps and military installations of the Taliban regime," Bush said in a televised address at 1 p.m. Sunday. "We are supported by the collective will of the world."
The attack began with strikes at air defense installations around the Afghan capital of Kabul and the southern city of Kandahar, Pentagon officials told CNN. Witnesses in Kandahar told CNN that at least three explosions rocked the city, and power was out.
The U.S. action follows several weeks of demands that the Taliban hand over suspected terrorist Osama bin Laden, whom U.S. officials hold responsible for the attacks. The Taliban have refused those demands.
Bin Laden has been living in Afghanistan as a guest of the Taliban, the fundamentalist Islamic militia that rules most of Afghanistan, since they seized power in 1996.
More than 5,000 people are presumed dead after hijackers plunged fuel-laden commercial jetliners into the Pentagon and each of the World Trade Center's twin towers on September 11. A fourth jet crashed into a Pennsylvania field after passengers tried to overpower the hijackers.
The United States began moving warships, aircraft and troops to southwest Asia in the weeks after the attacks. At the same time, U.S. diplomats worked to assemble a broad coalition of nations to support an international campaign against terrorism, including its NATO allies, Russia, Japan and moderate Arab states such as Jordan, Egypt and Saudi Arabia.
The Bush administration began sharing the results of its investigation into the September 11 attack with key allies, including the NATO countries and Pakistan, on October 2.
The United States designated bin Laden's al Qaeda organization a terrorist group in 1999. The organization has maintained training camps in Afghanistan for several years, and those camps were the target of a 1998 U.S. strike after bombings at U.S. embassies in Kenya and Tanzania killed more than 200 people.
Bin Laden faces criminal charges in the United States in connection with those bombings, and testimony in the trials of four men convicted of those attacks linked them to al Qaeda.