Updated

Canadian authorities investigating an alleged homegrown plot to blow up buildings in Ontario said Monday more arrests were possible as part of a wider probe into terrorist cells in at least seven countries, including the United States.

The Toronto Star, citing a U.S. counterterrorism official it did not name, said investigators were combing through evidence seized during Saturday's raids looking for connections between the 17 arrested suspects and at least 18 other Islamic militants detained in the United States, Bangladesh, Bosnia, Britain, Denmark and Sweden.

"This investigation is not finished," Royal Canadian Mounted Police assistant commissioner Mike McDonell told the Canadian Broadcasting Corp. on Monday. "Anybody that aided, facilitated or participated in this terrorist event will be arrested and prosecuted in court."

In an interview with National Public Radio, McDonell said the probe had expanded beyond Canada.

"We are working with and sharing our information with our allied countries," he said.

CountryWatch: Canada

The arrests were made Friday and Saturday after the group acquired three tons of ammonium nitrate from undercover Mounties in a sting operation, the Toronto Star has reported. The fertilizer can be mixed with fuel oil or other ingredients to make a bomb.

That is three times the amount of fertilizer used in the 1995 Oklahoma City bombing, McDonell said. The bombing of the Murrah Federal Building on April 19, 1995, killed 168 people and injured more than 800.

"For various reasons, they appeared to have become adherents of a violent ideology inspired by al-Qaida," Luc Portelance, the assistant director of operations with CSIS — Canada's spy agency, said Saturday.

Officials said the operation involved some 400 intelligence and law-enforcement officers and was the largest counterterrorism operation in Canada since the nation's Anti-Terrorism Act was adopted after the Sept. 11 attacks. The Star reported that the investigation began in 2004 with the monitoring of Internet chat rooms.

"We've been investigating them for some while and it got to the point where we could no longer control the risk," McDonell told NPR on Monday.

A prayer leader at a storefront mosque west of Toronto said several suspects prayed daily there but never spoke of hurting others.

"I will say that they were steadfast, religious people. There's no doubt about it. But here we always preach peace and moderation," Qamrul Khanson, an imam at the one-room Al-Rahman Islamic Center for Islamic Education, said Sunday.

The 40-50 Muslim families who worship at the mosque were astonished, he said, to learn that police had arrested 12 adults, ages 19 to 43, and five suspects younger than 18 on Friday and Saturday, charging them with plotting an attack in southern Ontario. Two Americans who met with the suspects also are in custody.

Secretary of State Condoleezza Rice said the operation was "obviously a great success for the Canadians. They're to be congratulated for it."

The 17 suspects represent a spectrum of Canadian society, from the unemployed to a school bus driver to the college-educated. The 12 adults live in Toronto, Mississauga and Kingston, Ontario.

Police said the suspects, all citizens or residents of Canada, had trained together. The oldest suspect, Qayyum Abdul Jamal, often led prayers at the storefront mosque.

Khanson said Jamal's Friday night prayers were "more aggressive" than those of other prayer leaders, but there was no talk of hostility or terrorism.

The modest mosque is sandwiched between The Cafe Khan, which offers Pakistani kabobs, and a convenience store in Mississauga, a city of 700,000 people with many immigrants. Mohammed Jan works at the cafe and said several suspects often came in for snacks after prayers.

"It's pretty shocking. They used to come every day and they just seemed normal," Jan said. "I definitely didn't find their behavior suspicious."

Neighbors said Jamal's wife drove a school bus, and he was always home and did not seem to work regularly. The couple has three small children, neighbors said.

Jerry Tavares of Brazil lives two doors down from Jamal's home. He said Jamal was unfriendly and rarely interacted with the neighbors.

"I wasn't surprised," the construction worker said, adding that he was afraid and intends to move out of the neighborhood with his wife and toddler. "You never know who lives next door."

A woman in a burqa peeked out from behind a curtain but would not answer the door at Jamal's home in a brick townhouse rental compound.

Another neighbor, Peter Smith, said a half-dozen SWAT team officers converged on the home Friday evening and began screaming at the family to get outside and get down on the ground. Even the young children were handcuffed, Smith said.

"Other kids were yelling, 'Terrorists! Terrorists!' and they were asking their mom, 'Mom, are we terrorists?"' he said.

Nada Farooq, the wife of 20-year-old suspect Zakaria Amara, described how police crashed into the family's home as the couple played with their 8-month-old baby. Family members were moved to the garage and her husband was taken away, she said.

"They're not guilty," she told CTV News. "They're still innocent until proven guilty and yet they're taking measures as though they're monsters."

FBI Special Agent Richard Kolko said in Washington there may have been a connection between the Canadian suspects and a Georgia Tech student and another American who had traveled to Canada to meet with Islamic extremists to discuss locations for a terrorist strike.

Syed Haris Ahmed and Ehsanul Islam Sadequee, U.S. citizens who grew up in the Atlanta area, were arrested in March.

The 17 suspects are scheduled to appear again in court Tuesday.

Khanson said at least three suspects regularly prayed at the Al-Rahman Islamic Center for Islamic Education.

"I have faith that they have done a thorough investigation," Khanson said of authorities. "But just the possession of ammonium nitrate doesn't prove that they have done anything wrong.

"We value our Canadian culture and we would never allow any links with the so-called Taliban or al-Qaida."

Rocco Galati, a lawyer for two of the men from Mississauga, said: "Both of their families are very well-established professionals, well-established families, no criminal pasts whatsoever. That's why we're anxious to see the particulars of the allegations against them."

He described Ahmad Ghany, 21, as a Canada-born health sciences graduate of McMaster University whose father, a physician, emigrated from Trinidad and Tobago in 1955.

His other client, Shareef Abdelhaleen, 30, is an unmarried computer programmer who emigrated from Egypt at age 10 with his father, he said.

Two suspects, Mohammed Dirie, 22, and Yasim Abdi Mohamed, 24, already are in an Ontario prison serving two-year terms for weapons possession. The Somali immigrants, who lived in Kingston, Ontario, were arrested Aug. 13 after crossing the Peace Bridge from Buffalo, N.Y., into Fort Eire, The Buffalo (N.Y.) News reported.

Another imam, Aly Hindy, said he knew nine of the suspects and complained that CSIS has unfairly targeted his mosque and congregants for years.

"They have been harassed by CSIS agents and this is what they come up with?" Hindy said. "I'm almost sure that most of these people will be freed."