They were our neighbors.

Twelve of the 19 men suspected of killing 5,000 innocents, threatening our freedom and edging our country toward war lived in our midst, seven in Delray Beach and five in Hollywood.

They lounged at a pool in Deerfield Beach, dined at a trendy Delray Beach night spot and drank at a popular Hollywood watering hole.

The 12 were among those named as hijackers Friday by the U.S. Justice Department. Federal authorities also made their first arrest in the worldwide investigation of Tuesday’s terrorist attacks.

Justice Department spokeswoman Mindy Tucker said the person arrested was a “material witness.” The arrest was made in New York, but the person arrested was not identified.

Unnamed federal investigators also indicate that Atlanta may have been targeted by terrorists, according to The Associated Press.

Meanwhile, the search continues. A list of more than 100 people was distributed to thousands of local police departments, the Federal Aviation Administration, border patrols and FBI field offices, Attorney General John Ashcroft said.

On the third day after the world’s deadliest terrorist attack, the loss grew ever larger — roughly 5,000 dead, 4,800 injured.

But even as more pieces came together, the bigger picture remained unclear: Why here? Who paid? Are they still in our midst?

Trained in S. Florida

As federal officials traced leads, it became clear that Mohamed Atta, 33, and Marwan Al-Shehhi, 23, who may have piloted two hijacked jets into the World Trade Center towers, had lived at several addresses and honed their flying skills in South Florida.

Atta was on American Airlines Flight 11, the first plane to crash into the World Trade Center. Al-Shehhi was on United Flight 175 out of Boston, which crashed into the south tower of the Trade Center minutes later.

Atta and Al-Shehhi lived at 1818 Jackson St., Hollywood, from May 13 to June 13, according to the building’s former owners. The small second-floor apartment rented for $600 per month and was sparsely furnished.

Al-Shehhi left behind a single piece of mail: A letter from United Airlines containing information about his membership in Mileage Plus, the company’s preferred frequent flier program.

On Friday, cleaners were scrubbing walls, floors and shelves to remove black fingerprint dust and stains from a chemical used to detect traces of blood. The residue was left by FBI and Broward Sheriff’s Office investigators who went through the apartment inch by inch, even tearing out sink drains, in their search for clues.

Atta was born in the United Arab Emirates and is thought to be Al-Shehhi’s cousin, according to The Associated Press.

Henry George, owner of SimCenter, a flight school at Opa-locka Airport, said Atta and Al-Shehhi trained together on two days in late December.

“They said they needed the simulator training because airlines in their country required exposure to jet aircraft,” he said.

Richard Surma, owner of the Panther Motel, 715 S. Ocean Blvd., Deerfield Beach, came to grips with the fact that his renters appeared to be part of the suicide attacks.