The FBI and local police are investigating a Miami-area mystery: Who dug a narrow tunnel that burrowed beneath a road and pointed toward a quiet suburban bank branch office.

FBI spokesman Mike Leverock said Jan. 30, that officials were notified after a motorist reported what looked like a sinkhole in a street near a Chase Bank branch in Pembroke Pines.

Investigators found an entrance hole in a nearby wooded area that contained a small electric generator and some electrical cords. The tunnel led under the road toward the bank, a distance of about 50 yards and it was only about 2 feet wide.

"The only thing I've ever seen like this is in the movies. This is truly a unique case here," Leverock said. "It's very small, very claustrophobic."

Investigators said the tunnel appeared to be dug by hand using tools such as a pickaxe, with a small wagon used to transport dirt and rock outside, Leverock said. A small ladder and a pair of muddy boots were also found inside.

A cadaver dog determined there were no bodies inside the tunnel. It wasn't immediately clear how long the underground structure had been there.

"They could have been here a week ago, last night. We don't know at this time," Leverock said.

Heavy equipment, including a backhoe, was brought in to dig up the tunnel.

"It's going to be a while," Leverock said of the investigation. "We're going to dig up the whole thing."

There was no robbery at the bank, no arrests have been made and no suspects were immediately identified. The bank remained open Jan. 30, although some drive-up windows near the tunnel were closed.

Pembroke Pines is about 20 miles southwest of Fort Lauderdale.

The FBI asked anyone with information about the tunnel or anyone who may have noticed people in the area during the night to contact the bureau's South Florida field office at 754-703-2000.