By Daniel Bases and Edward Krudy

NEW YORK (Reuters) - An unprecedented tidal surge in northern New Jersey on Tuesday flooded three towns with a wall of water well over 5 feet high in the wake of Hurricane Sandy, prompting the evacuation of thousands of people from their homes.

The towns of Moonachie, Little Ferry and Carlstadt were underwater after the swollen Hackensack River breached its barriers just after midnight.

"We've been involved since last night with urban search and rescue with the local folks in Moonachie and Little Ferry. We've saved hundreds already," New Jersey Governor Chris Christie said in a televised press briefing Tuesday morning.

"It was not a dam or a levee, it was just a natural berm that was overwhelmed by the tidal surge, that was an unprecedented tidal surge," a raspy voiced and haggard looking Christie said.

The area located in Bergen County was hit with the tidal surge between midnight and 1:30 a.m. giving residents almost no warning. The surge came after the brunt of the storm had passed. Sandy had dropped below hurricane status just before it hit the coast further south in New Jersey on Monday evening.

"From start to finish this wall of water, in some places a wave much higher than five feet, hit this unprepared area. The full impact was felt in less than 30 minutes," said Jeanne Baratta, chief of the Bergen County Executive.

"There are probably more than 2,000 residents affected by this and a lot do not realize they cannot go back home tonight," Baratta told Reuters by telephone.

Initially there was confusion as to what actually happened with speculation the river had overflowed its banks countered by early reports from the New Jersey State Police that a levee had in fact broken in the borough of Moonachie.

There were no immediate reports of any fatalities and rescue workers have taken out several hundred residents from the danger zone to temporary shelters. Others left of their own accord.

"They are wet and they are cold and they have lost their homes and their property. It is very sad," Baratta said.

"We are in rescue mode," she said, adding that the three towns had been "devastated" by the flood waters.

While low tides might pull some of the extra volume of water out of the area, officials were concerned it would all come flooding back with the upcoming high tide on Tuesday evening, leaving conditions unsafe for residents.

Baratta described a scene of house-to-house searching by rescue teams using boats and trucks to move residents to safety at a nearby school in Teterboro. Teterboro is home to a regional airport heavily used by corporate jets and smaller aircraft.

(Reporting By Daniel Bases and Edward Krudy; Editing by Claudia Parsons)