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A bank heist may have collapsed on itself when a Florida repair crew tending to a sinkhole discovered it was actually an underground tunnel leading to a Chase branch, the FBI said.

The tunnel was found Tuesday night in Pembroke Pines after city workers discovered an underground passage with a power cord running through it, FBI Special Agent Michael Leverock said Wednesday.

Authorities followed the tunnel approximately 50 yards and found it ended near a Chase Bank branch location. FBI

The two feet by two feet wide tunnel led to a nearby Chase Bank location but did not make its way underneath the branch.

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"The FBI was called given this is a possible bank burglary," Leverock said. "We traced the hole from the wood line approximately 50 yards until it hits the bank."

Authorities found a winch, a device to pull rope, that was used to bring in a small wagon inside the tunnel, Leverock said. There was also a pickaxe and a small generator in the passage.

A dog investigates where a tunnel was found in Pembroke Pines, Florida, on Jan. 30, 2019. Dan Grossman / WTVJ

Chase told NBC News it was working with authorities on the investigation and referred questions to the FBI.

The tunnel was just a few feet under the ground, according to the FBI. A cadaver dog was sent in but did not find anyone inside.

"It's a puzzle," Leverock said. "I can't imagine how they did it. As well as claustrophobic."

Authorities are still investigating how far the passage extends since recent rains may have caused portions of it to collapse, Leverock said.

"I would like to say I saw something like this in movies, however this hole is so small ... Yeah, it’s unique," he said.

Investigators have no suspects yet but believe there was more than one person involved.