WASHINGTON -- Some of the al-Qaida operatives whose activities led to a U.S. security warning last month have been captured, while others remain at large, U.S. counterterrorism authorities say.

"We have received a lot of good information from these detainees over the past several weeks and corroborated the fact there were active plans, ongoing, to conduct another attack in the United States," said William H. Parrish, a top intelligence official with the Homeland Security Department, during a recent interview with The Associated Press.

"This attack, as they indicated, was probably going to be multiple attacks, simultaneous," he said.

The al-Qaida members include some lieutenants operating in Saudi Arabia. Their leader, Abu Bakr al-Azdi, turned himself in in June; his deputy was killed in a recent shootout with Saudi forces.

"We also know there were also other members involved with this planning that are still loose," Parrish said.

Threat remains

Parrish, the acting assistant secretary for information analysis at Homeland Security, said the threat posed by this group remains one of the top domestic terrorism concerns.

On Sept. 4, the department issued a warning to security personnel suggesting an al-Qaida attack was in the works. It offered a number of potential threats; atop the list were concerns terrorists would again hijack airplanes and use them as weapons.

But the precise nature of the threat remains unclear. Enter Parrish, whose charge is to turn vague, uncertain intelligence into coherent, useful warnings for police, emergency workers and corporate security officials.

He now has about 60 intelligence analysts working for him -- a tiny shop compared with operations at the CIA and FBI. His group also must find a role distinct from the Terrorist Threat Integration Center, the new operation designed to share information between the FBI, CIA and other agencies on terrorist plots.

All that would seem to leave little room for Parrish's operation, which is part of the larger Information Analysis and Infrastructure Protection Office at Homeland Security. Indeed, many initially believed that Homeland Security would perform the function eventually given to the threat center.

Intelligence gathering

While working with state, local and corporate security personnel, Parrish also has some authority to direct intelligence-gathering by the CIA and other agencies to suit his needs.

For example, Homeland Security officials are pushing for U.S. interrogators to press al-Qaida prisoners to find out if the organization has the know-how to pull off the scenarios that members describe, he said.

If the prisoner talks of a plot to blow up a major suspension bridge, for example, Parrish wants to find out if Osama bin Laden's training camps held classes on the finer points of such bridge design.

"How many mechanical engineers does he have sitting on his bench?" Parrish said. "How many people does he have that know and understand where the structural weaknesses are in a bridge to be able to affect them? What were those skill sets that he taught in the training camps?"

Parrish also has customs and immigration officers work directly with intelligence analysts to advise them on what sort of information would be useful to their colleagues in the field.

'Spectacular attacks'

Like others, Parrish says he wonders why al-Qaida has not attacked inside the United States yet.

"Al-Qaida has always been focused and committed to the spectacular attacks," Parrish said. "The individual suicide bomber, although certainly within bin Laden's grasp to be able to execute, may not fit into that strategy."

But that could change, he warned.

"I think at some point, in time, like any organization, you go back and review that strategy," he said.