Residents of New Jersey were counting the cost of super-storm Sandy with thousands displaced by flooding and many homes still underwater.

Three thousand people were forced to leave their homes, Sky News reported.

Many of them were rescued by the National Guard and evacuated to temporary shelters.

At one evacuation centre at a school in the town of Moonachie on Tuesday, hundreds of people were arriving to spend the night.

Three generations of the Leo family fled their home in nearby Little Ferry as the floodwaters rose.

Mike Leo said the situation had been "nerve wracking".

Police lieutenant, Dwane Razzetti, who is an emergency management coordinator in New Jersey, said the scale of the devastation was "almost unprecedented".

Officials said the storm had exceeded experts' worst predictions, Sky said.

Some of those worst affected are residents of trailer parks.

Many fled before the storm arrived, but 69-year-old Raymond Neilsen stuck it out, afraid of crime.

He said the storm had been the worst he had ever seen.

President Barack Obama is planning to visit New Jersey later on Wednesday to see the damage to the state where the storm made landfall on Monday.

Obama has cancelled campaign events in battleground states to visit storm victims.

His Republican challenger Mitt Romney is planning three campaign rallies on Wednesday in Florida, the largest competitive state.