Federal agents descended on a working-class neighborhood in this old steel town near Buffalo Friday night, raiding several houses and making arrests, police and witnesses said.

U.S. officials in Washington, speaking to The Associated Press on condition of anonymity, said five men of Yemeni descent were arrested on suspicions they were operating as a terrorist cell on U.S. soil.

Lackawanna Mayor John Kuryak said he was informed six months ago that the FBI was doing an investigation here as a national security matter.

"When you first hear about it, you do get that initial shiver. You almost tell yourself, 'Not in your back yard. Not in my community.' But that was for a split second," he said. "No one can be that naive or take anything for granted these days since 9-11."

Late Friday, police and FBI agents still had one street blocked off in the area where neighbors say at least four houses, a garage and an Arab social club were raided. Agents were seen taking two boxes and a blue cooler from an apartment above an Arabian foods deli.

Lackawanna Police Capt. Ronald Miller confirmed there were arrests in this city just south of Buffalo. But he would only say those arrested were American citizens.

One man, Albaneh Mosed, said FBI agents burst into their home and arrested his 24-year-old brother, Shafal Mosed. He denied his brother had any links to the Al Qaeda terrorist network.

"If he was a terrorist I'd be the first to know," Albaneh Mosed said.

Mosed said his brother, who is married with a 3-year-old child, attended community college and recently got a job as a telemarketer.

FBI spokesman Paul Moskal wouldn't disclose or confirm any of the men's identities.

Ahmed Jamil, who was painting at one house raided by the FBI, said about a dozen agents burst in looking for a man in his 20s. The man was not home, he said. Jamil, who lives in the neighborhood, said the house belongs to the man's father-in-law.

Jamil said the agents searched for a half-hour and left the house a mess. He said the son-in-law occasionally filled in for the leader at the Lackawanna Islamic Mosque two blocks away. Jamil didn't believe any of the men had ties to Al Qaeda.

Phone messages at the mosque were not immediately returned.

"They went to Pakistan, and I'm absolutely sure their purpose was to further their Islamic education because sometimes they led the prayers in the mosque," Jamil said. "And they have no other intentions besides that."

Dr. Khalid Qazi, president of the American Muslim Council of Western New York, said he was told the investigation started when the local Muslim community reported suspicious activities to the FBI.