Five young Muslim American men from the Washington suburbs who disappeared late last month were detained in Pakistan on Wednesday in a police raid on a house linked to a militant group, American and Pakistani officials said.

One of the men had left behind an 11-minute video calling for the defense of Muslims in conflicts with the West and suggesting that "young Muslims have to do something," said one person who had seen the video, describing it as a farewell of sorts. Another official who viewed it called the video "disturbing," though he said it was not a martyrdom video of the kind sometimes made by extremists planning suicide attacks.

The five young men were detained at a house in Sargodha in Punjab province that was occupied by Khalid Farooq, the father of one of the young men, Umer Farooq, according to an official familiar with the case. The elder Farooq is believed to have ties to Jaish-e-Muhammad, a banned Pakistani militant group, the official said. Pakistani press reports also said security officials had linked the house to the militant group.

The men, ranging in age from the late teens to early 20s, were not accused of any crime; their intent remained mysterious, and both American and Pakistani officials emphasized that they were still gathering facts. One of the men, Ramy Zamzam, 22, is a dental student at Howard University, where he received an undergraduate degree this year with a major in biology and chemistry, according to his Facebook page.

But their disappearance and resurfacing in Pakistan came amid broad concern in the United States about a rash of terrorism cases that appeared to be homegrown.

Nihad Awad, national executive director of the Council on American-Islamic Relations, an advocacy group that is working with the families of the young men, cautioned against hasty conclusions about the episode during a news conference in Washington with other Muslim leaders.

But Awad, who said he had seen the video, and the other leaders said the case - along with the recent recruitment of young Somali-American men in Minnesota by a violent group in Somalia - suggested that at least a small number of young American Muslims were drawn to extremist views. They pledged to start a nationwide campaign to counter such attitudes.

The five men, some of whom knew each other from their mosque in Alexandria, Va., disappeared from their homes in late November, officials said. Concerned family members contacted local imams and the Council on American-Islamic Relations, or CAIR.

Officials with the group met with the families on Dec. 1 and put them in touch with the FBI the same day, said Ibrahim Hooper, a spokesman for the group.

Hooper said neither the mosque - the ICNA Center, associated with the national Islamic Circle of North America - nor the Virginia families supported extremism or violence. "The Muslim community has taken the lead on this case in terms of taking it to law enforcement," Hooper said.

The Justice Department, in a statement, said the FBI "is working with families and local law enforcement to investigate the missing students and is aware of the individuals arrested in Pakistan."

It continued: "We are working with Pakistan authorities to determine their identities and the nature of their business there, if indeed these are the students who had gone missing."

American and Pakistani officials said the five men flew from Dulles International Airport outside Washington and landed in Karachi, Pakistan, on Dec. 1, the day their families approached the FBI. They traveled to Hyderabad, Pakistan, and then to Lahore, where they spent five days before moving on to Sargodha.

Asked for assistance by the FBI, Pakistani security officers tracked the men to Farooq's house, where they were taken into custody on Wednesday, the officials said. In addition to Umer Farooq, two of the other men - named in Pakistani press accounts as Ahmed Abdullah and Wakar Khan - were described by officials as of Pakistani descent. Zamzam's family is Egyptian, and a fifth man, Aman Yasser, is of Yemeni descent, according to one official. Some were born abroad, but all are now U.S. citizens, American officials said.

Old friends of Zamzam's seemed incredulous at the news that he had been detained in Pakistan. Zohra Alnoor, a student at Northern Virginia Community College, met Zamzam two years ago through the Muslim Students' Association D.C. Council, an umbrella organization joining Washington-area colleges. Zamzam helped organize and competed in a yearly quiz competition about Islamic texts and issues, she said.

"He was very devout, he wouldn't date women," she said. But she said she could not recall his expressing strong political beliefs.

Zamzam lives with his parents and younger brother in a basement apartment in Alexandria, Va. The brother, who said he goes by the nickname Zam, said in an interview that Zamzam "is a good guy. He's a normal Joe." He said his brother earned a 4.0 grade point average and wanted to become a dentist.

An upstairs neighbor, 16-year-old Peter Max-Jones, called Zamzam "very intelligent, very kind, very helpful. Good citizen, all around." He said Zamzam's family was "very patriotic, very quiet."

He added: "They're never outside. They're always at home, studying."

A year ago, in a Facebook message to a woman who had questioned the need for women to cover their heads or faces, a person who identified himself as Zamzam responded by saying that the Quran "clearly instructs the believing women to cover themselves," adding that "those that don't, then woe to them for a day where all will be held accountable."

At the ICNA Center in Alexandria, which occupies a modest brick building without a sign at the edge of a residential neighborhood, most people arriving for prayers on Wednesday night declined to comment.

One man who would not give his name acknowledged that he knew some of the young men and described them as unsophisticated.

"They didn't even know the price of beer," the man said.

According to documents posted on the Web, Zamzam led a drive last year by young Muslims affiliated with the ICNA Center to raise money to build a new mosque. The plan was to persuade 500 mosques around the United States each to donate $500 toward the cost, and Zamzam and 16 other activists named the effort Project 500.

"We hope to inspire the Muslim youth all across America to step up and how everyone that we can get things done and prove we are the future of this Muslim Ummah," or community, said a statement on Project 500's now-defunct Web site. The site displays no hint of radicalism.