US 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 US government.
State Department spokesman P.J. Crowley told reporters that the US officials who visited the five young Americans were US Embassy security officers and FBI officials. He said US 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 November. 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 US 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 US 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.