Updated

Khalid Shaikh Mohammed, the suspected mastermind of the Sept. 11 terrorist attacks, was arrested Saturday in Pakistan, both senior Pakistani officials and U.S. intelligence sources have confirmed.

Pakistani Information Minister Sheikh Rashid Ahmed said Mohammed was one of three men arrested in a 3 a.m. raid in Rawalpindi, a city near Islamabad.

"It's hard to overstate how significant this is," White House spokesman Ari Fleischer said of the arrest. "It's a wonderful blow to inflict on Al Qaeda."

Conflicting reports exist about Mohammed's future. Reuters news service has reported that Ahmed said Mohammed will be extradited to the United States. But U.S. officials would not confirm whether that was true.

American officials, speaking on condition of anonymity, said CIA officers and Pakistani authorities carried out the operation that led to Mohammed's capture. However, senior Pakistani officials told Fox News that U.S. officials were not directly involved in the arrests themselves.

Information for the arrests came from raids conducted in Pakistan over the last few weeks.

Mohammed, 37, is one of the FBI's most-wanted terror suspects, and the U.S. government had offered up to $25 million for information leading to his capture.

U.S. officials have described him as a key Al Qaeda operative and the organizer of the terror plot that sent hijacked passenger jets crashing into the World Trade Center, the Pentagon and a Pennsylvania field, killing more than 3,000 people.

Mohammed, a Kuwait-born Pakistani national, has been linked to last April's bombing of a synagogue in Tunisia. At least 19 tourists, mostly Germans, were killed.

He has also been charged in connection with plots in the Philippines to bomb trans-Pacific airliners and crash a plane into CIA headquarters. Those were broken up in 1995.

Mohammed is the uncle of convicted 1993 World Trade Center conspirator Ramzi Yousef.

Mohammed's older brother also is a member of Usama bin Laden's Al Qaeda terror network and another brother died in Pakistan when a bomb he was making exploded.

Another man of Middle Eastern origin was arrested in Saturday's raid but has not been identified. The third man was a Pakistani identified as 42-year-old Abdul Qadoos, a 42-year-old member of one of the country's main religious parties, Jamaat-e-Islami.

Interior Ministry spokesman Iftikar Ahmad said Qadoos was linked to a terrorist organization but refused to identify it. He added that Qadoos had trained in Afghanistan.

Senior government officials said the three men were arrested about 3 a.m. local time Saturday at a house where Qadoos lives with his father.

But Omar Qadoos, Ahmed's cousin, said only Ahmed, his wife and two children were in the house. There also was a guard outside, he said.

"The police pounded on the gate and then they rushed through. There was some firing, but no one was hurt and then they beat the guard and broke the lock on the front door," Omar Qadoos said.

He said police held the family at gunpoint while they collected cassettes, a computer and computer discs, leaving the floor littered with clothes, papers and other items.

Mohammed barely evaded capture in a raid about a week ago in the southwestern town of Quetta, a Pakistani government source said. During that operation, a Middle Eastern man, possibly of Egyptian origin, was arrested, according to the source, who spoke on condition of anonymity.

"At the time of that raid in Quetta the authorities were looking for Khalid Shaikh but he escaped and from there they followed him to Rawalpindi," the official said. "They got information from the man they picked up in Quetta and from phone calls until they tracked him down to Rawalpindi."

In Washington, the FBI refused to confirm Mohammed was arrested or say whether the bureau was involved.

President Gen. Pervez Musharraf has said a small number of FBI agents are in Pakistan but only to provide intelligence on Al Qaeda or Taliban fugitives from neighboring Afghanistan.

However, Pakistani police and intelligence officials say FBI agents have been involved in nearly every important terror arrest in Pakistan.

The Pakistani government says it has handed over more than 420 Al Qaeda and Taliban suspects to U.S. custody.

The Associated Press contributed to this report.