SOUTH BRUNSWICK — They never touched the floor — that would have set off an alarm.

They didn’t appear on store security cameras. They cut a hole in the roof and came in at a spot where the cameras were obscured by advertising banners.

And they left with some $26,000 in laptop computers, departing the same way they came in — down a 3-inch gas pipe that runs from the roof to the ground outside the store.

Police believe that’s how some brazen bandits managed to swipe 20 Apple notebooks early this morning at a Best Buy on Route 1 in South Brunswick without detection.

"High level of sophistication," said Detective James Ryan, a police department spokesman. "They never set off any motion sensors. They never touched the floor. They rappelled in and rappelled out."

Employees discovered the missing laptops, as well as a gaping hole in the ceiling, when they arrived to work around 6:30 this morning.

The thieves left boot prints on the gas pipe, which runs up the side of the building in Monmouth Junction, Ryan said.

On top of the building, they used a saw to cut through several inches of rubber and insulation, then sliced a 3-foot-wide square in the metal roof, he said.

Once inside, the burglars dropped 16 feet to 10-foot-tall racks — avoiding contact with the floor, where motion sensors would have set off an alarm. They snatched the notebooks from the racks, then went back out through the roof.

The effort was daring and unusual, said John Harris, an expert in security who has consulted on thousands of burglaries.

"I would say they were a professional crew," said Harris, who is based in Atlanta, Ga., but does work throughout the nation. "At least I’ve never dealt with anything like this. From time to time, people break in, but not usually through the roof."

It’s a first for South Brunswick police and Detective Ryan, who said he’s seen similar burglaries but never anything that required this much effort. The thieves knew the layout of the store and apparently knew the banners would block the view of security cameras, he said.

"The tools they had to bring, the alarms they had to circumvent — it certainly required a lot of high-level planning," Ryan said.

Police think it may not be an isolated incident, and that the crew — which had to include at least 2 or 3 people — might have hit other locations before. The investigating officer, Detective John Penney, will share his notes with other law enforcement agencies around New Jersey.

The corporate offices of Best Buy declined to comment.

Anyone with information about the incident is asked to call Penney at (732) 329-4646.