Anatomy of Attack on Pakistan's U.S. Consulate

March 2, 2006 — -- At least four people, including a United States diplomat, were killed and more than a dozen injured when an extremely powerful bomb went off in the area around the American consulate in Karachi, Pakistan.

"When this happened, I thought this might be an accident, but then I saw the smoke," said one survivor. "And I said, 'Oh, my God, it's a blast.'"

According to a video security tape described to ABC News, a U.S. consulate Toyota Land Cruiser with an American diplomat inside approached the back street to the consulate at 8:58 a.m.

Parked on the street in a spot reserved for Pakistani naval officers, the suicide bomber waited for 18 minutes and then backed into the Land Cruiser. The subsequent blast was so powerful that it blew the fully armored U.S. car, which weighed more than 3 tons, 40 feet into the air and into the Marriott Hotel parking lot.

"The explosion caused this six-foot crater in the cement," said Gretchen Peters, an ABC News producer who was on the scene. "This was a massively powerful explosion, and the results are grisly."

President Will Still Go to Pakistan

The State Department identified the dead American as David Foy, 52, of North Carolina. He had worked at the consulate since September.

In India President Bush promised the attack would not keep him from visiting Pakistan this Saturday.

"The bombing that took place prior to my trip is an indication that the war on terror goes on, and free nations must come together to fight terrorism," he said.

Al Qaeda Operations Based in Karachi

As of now, no group has claimed responsibility, but the city of Karachi -- the largest metropolis in Pakistan -- is at the center of al Qaeda's operations.

Top al Qaeda commanders have been captured there, and American reporter Daniel Pearl was kidnapped and killed there. As for attacks against the U.S. consulate, which is seen as the No. 1 target, there have been two previous bombings.

"This attack, which was the largest in terms of the bomb size to date, was meant to embarrass the United States the day before the president arrives in Pakistan," said Richard Clarke, a former counterterrorism official and now an ABC News consultant.

ABC News' Maddy Sauer contributed to this report.