Another senior officer said the men wanted to fight jihad, or holy war, in northwestern Pakistan and against American troops in Afghanistan.
The young men apparently first tried to contact jihadist groups through Facebook and YouTube, then traveled to Pakistan to attempt personal meetings, a Pakistani diplomat in Washington said.
The case is another worrisome sign that Americans may be susceptible to recruitment to terrorist networks from within the United States. It comes on the heels of charges against a Chicago man accused of plotting international terrorism.
Yet in contrast to the Chicago case, police say the five captured in Pakistan failed to catch on with any terror network, and succeeded only in raising suspicions among locals, who reported them to Pakistani police.
U.S. officials in Pakistan have now visited the men in custody. Their disappearance from the Washington, D.C, area late last month -- with one of them leaving behind a militaristic farewell video saying Muslims must be defended -- prompted a frantic search by friends and family and an investigation by worried counterterrorism officials.
Javed Islam, a regional police chief in Pakistan, said the men wanted to join Islamist militants in the country's tribal area before crossing into Afghanistan and said they met with a banned organization, Jaish-e-Mohammed in Hyderabad, and with representatives of a related group, Jamat-ud-Dawa, in Lahore.
"They were asking to be recruited, trained and sent on jihad," Islam said.
But Islam said those groups turned them down because they did not have any "references" from trusted militants.
Islam said the arrested Americans had spent the past few days in Sargodha, 125 miles (200 kilometers) south of the capital, Islamabad, before their arrest.
The men used the social networking site Facebook and the Internet video site YouTube to try to connect with extremist groups in Pakistan, said S.M. Imran Gardezi, the press minister at the Pakistani Embassy in Washington. When they arrived in Pakistan, they took that effort to the street.
"They were trying to link up to some groups, but there is no evidence for now that there was a definite plan," Gardezi said.
Local Pakistanis became suspicious of the young men and tipped off police, he said. Police arrested the group in a home belonging to the uncle of one of the men. Gardezi said the uncle had past ties to extremist groups.
Gardezi said the men have not been turned over to the FBI and that Pakistan intended to carry out its own legal process.
Another Pakistani law enforcement official, Usman Anwar, the local police chief in Sargodha, told The Associated Press the five are "directly connected" to the al-Qaida terrorist network.
"They are proudly saying they are here for jihad" or holy war, Anwar said.
U.S. diplomats have met with the five men.
"We have had access to the five detainees," Secretary of State Hillary Rodham Clinton told reporters Thursday. She called the move "part of the usual outreach" of the U.S. government.
State Department spokesman P.J. Crowley told reporters that the U.S. officials who visited the five young Americans were U.S. Embassy security officers and FBI officials. He said U.S. consular officials are scheduled to meet with the five on Friday.
"We're in an information-gathering phase," Crowley said, adding that one question they sought to answer was why the five were in Pakistan. "We should just not draw any conclusions at this point," he said.
The five students were making preparations to voluntarily return to the United States several days ago, before they were detained, according to Nina Ginsberg, the lawyer for the families.
"The families had gotten indications that they had decided to come back," she said.
She said she has seen the farewell video, and while it was troublesome, "I don't believe it constitutes a crime. I don't think it goes over the edge of asking or directing people to commit acts of violence."
The young men's families asked the FBI for help after finding a farewell video left by the men showing scenes of war and casualties and saying Muslims must be defended.
"One person appeared in that video and they made references to the ongoing conflict in the world and that young Muslims have to do something," said Nihad Awad of the Council on American-Islamic Relations, or CAIR. The video has not been made public.
After the disappearance of the five men in late November, their families, members of the local Muslim community, sought help from CAIR, which put them in touch with the FBI and got them a lawyer.
The men range in age from 19 to 25. Three of the arrested Americans are of Pakistani descent, one is of Egyptian descent and the other has Yemeni origins, police officer Tahir Gujjar said.
One, Ramy Zamzam, is a dental student at Howard University. Pakistani police officer Tahir Gujjar identified three of the others under arrest as Eman Yasir, Waqar Hasan, and Umer Farooq.
The fifth young man was identified as Ahmed Mimi by a Pakistani government official in Washington, who was not authorized to discuss the case and spoke on condition of anonymity.
According to a Pakistani official who also spoke on condition of anonymity, the group applied for travel visas in the week leading up to Thanksgiving. On their visa applications, their stated reason for travel was to attend a friend's marriage and go sightseeing. They were arrested Monday, the official said.
Farooq's father, Khalid Farooq, also was detained. Pakistan police officials say the elder Farooq had a computer business in Virginia and shuttled between the U.S. and Pakistan. Investigators are still trying to establish what role -- if any -- he played in the men's alleged activities, officials said.
The men were arrested at a house in Sargodha, Pakistani officers said. Islam said investigators are sharing their findings with FBI officials now in Sargodha.
The American men have not been charged. It was not clear if they had been appointed lawyers.
Anwar said officers seized a laptop, jihadi literature and maps of Pakistani cities from the men.
Pakistan has many militant groups based in its territory and the U.S. has been pressing the government to crack down on extremism. Al-Qaida and Taliban militants are believed to be hiding in lawless tribal areas near the Afghan border.
The case is the latest in a series that will likely fan concerns among Western nations that their citizens -- specially of Pakistani origin -- are traveling to the country to connect with al-Qaida or take part in training or indoctrination sessions.
According to officials at CAIR, the five left the country at the end of November without telling their families.
After the young men left, at least one phoned his family still claiming to be in the United States, but the caller ID information suggested they were overseas.
A Howard University spokesman confirmed Zamzam was a student there but declined further comment.
Samirah Ali, president of Howard University's Muslim Student Association, said the FBI contacted her last week about Zamzam, and told her he had been missing for a week. Ali said she's known Zamzam for three years and never suspected he would be involved in radical activities.
"He's a very nice guy, very cordial, very friendly," Ali said.