Five men, including two father-and-son pairs, have now been arrested as federal law enforcement officers try to determine whether they have uncovered a network of Al Qaeda (search) supporters in Northern California.

Father and son Umer and Hamid Hayat were arrested over the weekend in Lodi, Calif., on criminal charges. Three Pakistani citizens are also being held on immigration violations. Lodi is an agricultural community 40 miles south of Sacramento.

Federal investigators were also pursuing leads related to the arrests in Sacramento and San Francisco, a federal law enforcement official told FOX News.

Two law enforcement sources have confirmed to FOX News that there is a connection between the Hayats and the Pakistani citizens.

Hamid allegedly received terrorist training and funding from the father, an ice cream truck driver, so he could carry out attacks on hospitals and large food stores in the United States. But FBI officials on Wednesday backed away from specific information regarding any type of planned attacks.

Hamid, 22, and his father, 47, are charged with lying to authorities about the son's alleged training at an Al Qaeda camp in 2003 and 2004 and money sent for training. Both are American citizens; the younger man was born in California.

Click here to view the criminal complaint (FindLaw).

The U.S. Immigration and Customs Enforcement (ICE) agents also have arrested Mohammed Adil Khan, Shabbir Ahmed and Khan's 19-year-old son, Mohammad Hassan Adil, for immigration violations. All three are citizens of Pakistan and Khan is affiliated with the Farooqia Islamic Center near Lodi, Calif. Ahmed is a citizen of Pakistan who currently functions as the Imam of the Lodi mosque.

Those three men are expected to eventually appear before an immigration judge.

Neighbors: Hayat Family Wasn't Suspicious

An FBI affidavit says Hamid Hayat first denied any link to terror camps, but then told agents he attended an Al Qaeda camp in Pakistan for six months.

A law enforcement source confirmed to FOX News that search warrants have been executed at two mosques, homes of the Hayats, as well as that of the Lodi Muslim Mosque's imam. The case is now described as "ongoing investigation by the JTTF," the joint terrorism task force. FOX News was told that the connection between the Hayat's and Khan Ahmed "is more than just a meeting, there are many connections, here and possibly Pakistan."

Les Kolb, a neighbor of the Hayats in Lodi, told FOX News on Thursday that the family never aroused suspicion. "We always bought ice cream off of his truck. They were friendly neighbors," Kolb said.

Kolb said neighbors knew the son and other members of the family were in Pakistan and that the father had been alone in the house for quite a while. However, Kolb said nothing at the house ever happened that stood out and he never would have suspected the family of being involved in any illegal activities.

A cousin of the younger Hayat, Usama Ismail, said he was in Pakistan with his relative and that Hayat never had terrorist training (search). He said his cousin went to Pakistan to marry and "never got into politics. All he talked about was cricket."

"We were always together," said Ismail, who lives down the street from the Hayats in a modest, blue-collar neighborhood. "He never went anywhere. He was always in the village."

Lodi's mayor, John Beckman, was meeting with members of the city's relatively large Muslim community to discuss how to deal with the media scrutiny and prevent a possible anti-Muslim backlash. A couple bias incidents have been reported since the arrests.

Both men were being held at the Sacramento County Jail. Umer Hayat's attorney, Johnny Griffin III, called the allegations "shocking" but said his client "is charged with nothing more than lying to an agent."

Agents removed boxes of photographs, videocassettes and fax machines were removed from the Hayat home over the weekend.

U.S. Magistrate Judge Peter A. Nowinski denied a bail request for the elder Hayat, saying he was a flight risk and a danger to the community. Hamid Hayat's attorney wasn't in court, and Nowinski set his bail hearing for Friday.

"Hamid advised that he specifically requested to come to the United States to carry out his jihadi mission," according to the affidavit. "Potential targets for attack would include hospitals and large food stores."

The affidavit discusses weapons training Hamid Hayat received and says, "during his weapons training, photos of various high ranking U.S. political figures, including President Bush, would be pasted onto their targets."

Umer Hayat told agents his son first became interested in attending terror training camps (search) during his early teenage years.

According to reports in the Los Angeles Times and The Sacramento Bee, Hamid Hayat was trying to return to the United States from Pakistan on May 29 when the FBI told its Sacramento office that he was on the federal "no-fly" list (search).

The Korean Air plane he was flying on was diverted to Japan, where Hayat was interviewed by the FBI and denied any connection to terrorism. He was allowed to fly to California, but was interviewed again on June 3-4. He then acknowledged spending time at the training camp, the affidavit said.

He voluntarily took a lie detector test, which the affidavit said indicated he was not telling the truth. Hayat then acknowledged spending time at the training camp, the affidavit said.

Brian Chavez-Ochoa, an attorney representing several members of the Lodi Muslim community in California, told FOX News on Thursday that Muslims there are very supportive of the investigations so long as they have hard evidence of any links to Al Qaeda.

"Cert if these allegations turn out to be true, they cannot be tolerated. Since 9/11 the Muslim community has been behind the government," Chavez-Ochoa said. "The allegations as they stand are against liberty, freedom, as well as the Muslim way of life ... their way of life is our way of life."

But Chavez-Ochoa warned the public against rushing to judgment as to whether the suspects are guilty or innocent before the justice system works its way through the matter. He also said the Muslim leaders in the Lodi community preach peace, not violence.

"They always preach against violence. The Muslim community is a loving community, peaceful … they're very involved in the community," he said, adding that attacks such as those that hit New York and Washington on Sept. 11, 2001, are "not typical of what this community in Lodi believes."

In Washington, President Bush said he had been briefed on the matter.

"I can assure the America people we are following every lead, we are doing everything we can to keep America protected," the president told FOX News' Neil Cavuto in an interview on Wednesday. He added that officials are doing "everything we can to bust up these terrorist networks."

FOX News' Claudia Cowan, Catherine Herridge and The Associated Press contributed to this report.