There were two signals.

If the suspected jihadists bit and tried to buy automatic weapons from the informant, this would trigger an antiterror dragnet across South Jersey and Philadelphia. "A symmetrical strike," FBI supervisor Robert Downey said.

But if something went wrong - if the guys with crew-cuts and flowing beards didn't show, or didn't take the bait - then "we had to be prepared to back away and not tip our hand," the supervisor said.

Also lingering in many minds Monday evening: the recent death of FBI agent Barry Bush during a North Jersey shootout.

Two signals. Go or stand down.

With a call at 9:07 p.m. Monday, agents moved forward - climaxing a 16-month terrorism investigation that included thousands of hours of human and electronic surveillance, some of it using provisions of the controversial Patriot Act.

For the FBI, it was a high-profile takedown. Even the case agent had a Hollywood name: Jack Ryan.

Things didn't go precisely as planned. Such raids rarely do. Yet 48 minutes after it all began, the six targets were under arrest. Two others were detained.

"We had been watching them for a long time and knew their patterns better than their families," said Downey, who directed the raid from a trailer parked at a Cherry Hill fire station. "It's like this: The Eagles practice all week and know what their roles are and what the game plan is, but you never know what your opponent's going to do. So you have to be ready for anything."

Five of the six arrested are charged with plotting to kill U.S. soldiers at Fort Dix. The FBI was tipped to their plan after they tried to copy a video of a training exercise in the Poconos. Justice Department spokesman Dean Boyd said agents made the arrests once it became clear the group appeared ready to act.

"Our view was, they had pretty much gotten to concluding the planning phase of this and were looking to obtain heavy weaponry - and if not from us, they were going to try to obtain it elsewhere," U.S. Attorney Christopher J. Christie said.

If convicted, the men each face about eight years in prison, under advisory sentencing guidelines. The sixth man is charged with helping them find the weapons to attack the base. Each is scheduled to appear at a bail hearing before a federal magistrate in Camden today.

Monday's raids at six locations were conducted by the FBI, the New Jersey State Police, the Philadelphia Police, the Camden County Prosecutor's Office, the Delaware River Port Authority Police, and U.S. Immigration and Customs Enforcement. The authorities used two helicopters, more than 100 officers, bomb squads, hostage negotiators, dogs, submachine guns, anti-surveillance equipment, an armored vehicle, hazardous-material crews, and several SWAT teams.

"They never had a chance to really resist," said New Jersey State Police Capt. Al Della Fave.

According to an affidavit filed by Ryan, the FBI informant set up a sting Monday night, luring two of the six men to a Cherry Hill apartment to buy AK-47 and M-16 assault rifles.

The meeting was set for 9 p.m. in Apartment 6B at the Hampshire House apartments.

Agents, troopers and police arrived hours earlier to prepare - and presumably to wire - the apartment. Other teams set up staging areas, and waited.

"It was an intricate puzzle, and everyone contributed a critical piece," said ICE agent-in-charge John Kelleghan.

9 p.m. A red Chevrolet pickup truck pulled into the apartment building parking lot. Right on time.

Agents recognized the men who got out: Shain Duka, 26, a strawberry blond with blue eyes, and Dritan Duka, 28, brown eyes, brown hair. Both brothers were born in the city of Debar when it was part of the former Yugoslavia. They had arrived in America in 1984 as young children but were now considered illegal immigrants. They worked for their father's roofing company.

Agents didn't know the third man, the driver, who waited in the pickup.

9:02 p.m. The Duka brothers entered Apartment 6B.

Within minutes, the FBI informant gave an arranged signal, a code phrase to agents listening, that the deal was done. "The Dukas never got control of the weapons," Downey said.

Agents rushed in, and Cherry Hill police officers stopped the driver, though they later released the man because he had nothing to do with the case. Ryan radioed the command post: "It just went down."

9:07 p.m. An FBI agent passed the news to the other teams.

9:08 p.m. Agents, troopers and police began simultaneous raids on two Cherry Hill homes, a Philadelphia apartment, and a stone bungalow in a South Jersey Pinelands community called Collings Lakes.

At the Cherry Hill apartment, Dritan Duka's home on Park Boulevard, troopers removed his wife and started to search the place.

At the Cherry Hill house, the Duka brothers' parents' home on Mimosa Drive, ICE agents arrested the father, Ferik Duka, detaining him as an illegal immigrant.

In Collings Lakes, meanwhile, agents and police moved along the fence surrounding the bungalow, past a dirt driveway and a couple of boats, toward the door, and a sign that said: "Free Weeds. Just Take."

This was the Atlantic County home of Agron Abdullahu, a baker for a Gloucester County grocery, who had arrived legally in the country in 1999 from Kosovo. There, he served as a sniper during its civil war. So this arrest made troopers nervous.

Abdullahu, though, didn't resist.

Inside, troopers seized an assault weapon, a handgun, a shotgun and 200 rounds of ammunition. Troopers also discovered what they thought was a bomb - something with "wire protruding from it," said New Jersey State Police Maj. John Hunt, and "a symbol etched on it that warned it was radioactive."

The bomb squad tested the object, which turned out to be nothing more than a piece of junk.

Neighbors said Abdullahu, wearing only his boxers, was hustled away in an armored vehicle.

9:12 p.m. Agents and troopers stormed the home of Mohamad Shnewer on East Tampa Avenue in Cherry Hill, where a bike with training wheels stood in the overgrown front lawn.

Shnewer, a naturalized U.S. citizen born in Jordan, is big - 270 pounds. The 22-year-old was a Philadelphia cabdriver. The FBI had already copied the hard drive of his laptop, where agents allegedly discovered jihadist images. Shnewer had told the informant, according to a secret recording: "My intent is to hit a heavy concentration of soldiers. . . . I assure you that I can hit an American base very easily."

As agents searched the home, neighbor Steve Bender said, a woman emerged and shouted: "My son don't do that! He is a hard-working guy."

Shnewer wasn't home, but a surveillance team was watching him: He was driving his cab, a white All City van, toward Philadelphia International Airport.

9:17 p.m. Agents and police arrived at the Philadelphia apartment of Serdar Tatar, a 23-year-old convenience store clerk born in Ankara, Turkey. He was the alleged inside connection - the guy whose family's pizza business had a pass to enter Fort Dix, and who allegedly provided the others with a map of the base.

Tatar wasn't home, either - and agents didn't know where he was.

A neighbor, Stacie Gandlina, said that when agents couldn't find a key to the apartment, she gave them a hammer they used to break in.

9:27 p.m. The team searching Dritan Duka's apartment got a surprise. Two troopers standing outside the home, Rodney Logan and George Gallagher, saw a gray Chevy Silverado pull into the parking lot. It was Eljvir Duka, the third Duka brother. Troopers recognized his car from photos they'd seen at a briefing.

They stopped the car and ordered Duka out. The 23-year-old put his hands up and lay on the pavement.

9:38 p.m. Shnewer's white van pulled into the airport queue to pick up a passenger, and agents decided to pounce. They wanted to grab him before he got too close to the busy terminal.

Agent Rich Macko, who had once been wounded on a raid, moved toward the driver's door, gun drawn. Agent Dave May, recently returned from a second tour as an Army Reservist in Afghanistan, came around the passenger side. He gripped an MP-5 submachine gun.

Macko identified himself and, according to a federal official, "the guy froze - a deer in the headlights look."

9:55 p.m. Across town, agents searching Tatar's apartment caught a break.

The final suspect came home.

Contact staff writer John Shiffman at 215-854-2658 or jshiffman@phillynews.com.

Inquirer staff writers George Anastasia, Sam Wood, Dwight Ott and Jan Hefler contributed to this article.