HOBOKEN, N.J. » National Guard troops delivered food and supplies to residents in this heavily flooded city across from Manhattan today as officials sent out a plea for boats, generators and volunteers.

Superstorm Sandy sent the raging Hudson River waters from one side of the one-square-mile city to the other Monday. Two days later, at least 25 percent of the community remained flooded, leaving many residents anxious about whether they could get out and municipal leaders struggling to get assistance to all those who needed it.

Tempers flared today at a staging area outside City Hall, where a man screamed at emergency officials about why food and water had not been delivered to residents just a few blocks away. The man, who would not give his name, said he blew up an air mattress to float over to a staging area.

City officials defended their response.

"The dimension and scope of this situation is enormous," Public Safety Director Jon Tooke said. "You have emergency operations at all levels — from local to federal — spread too thin across the city and the state, but we’re working on it."

Tooke said the estimated 20,000 people still stranded in their homes were being encouraged to shelter in place, and that high-water vehicles would get supplies to them. He said people with medical and other special needs were being taken out by trucks.

National Guard troops arrived Tuesday night, and today city officials were issuing an appeal for additional aid. They asked that people bring boats and generators to the staging area at City Hall, which was on dry ground.

"We are doing what we can but we really need more help," said the mayor’s spokesman, Juan Melli.

Dozens of volunteers answered the call to help go door-to-door to see if seniors and others needed water or other supplies.

Frank Bongiorno, an 80-year-old resident of a senior high-rise, said he walked down 15 flights to get out of his building, then waded through some low water to get to City Hall.

Wearing a sweatshirt too thin for rapidly dropping temperatures, Bongiorno said he needed to get out. "They finally gave us a sandwich today but it was this big," he complained, pinching his fingers about an inch apart.

Tooke said fuel had been delivered to the high-rise to get its generator back up and running.

This city of 50,000 with many narrow streets still retains its working-class grit, but also has come to be known as a great place for young professional families, including workers on Wall Street just across the river in Manhattan.

Before the storm hit, evacuation orders went out for people living in Hoboken’s many basement apartments and first-floor units.

Many were surprised by the extent of the flooding.

Samuel Scott Cornish, 34, who lives with his wife, Katie, and newborn son, Jack, in a luxury apartment complex on the border of Hoboken and Jersey City, said he was told to move his Subaru to a different area inside his building’s garage for safety before the storm, only to later discover it floating in water. The garage is now filled with water-soaked cars, including a BMW floating upside down.

Cornish said the storm itself was initially a bonding period with neighbors he once only nodded hello to.

But now that residents have been able to get outside their homes and see a bit of dry sidewalk for the first time in days, they are realizing the full scope of the damage and are getting antsy.

Cornish was deciding today whether to go to his parents’ house in Summit, which had no power.

"I’m debating, no power and a colder house in Summit, or stick it out here with some auxiliary power that will only last until the building runs out of diesel," he said.

In Cornish’s building, the generators powered only the hallways. He said doors were open and neighbors were sharing; some had refrigerators plugged in hallway outlets or worked on laptops.

At one condo building where power was out, residents decided to celebrate Halloween today afternoon, sending children door-to-door in their costumes.

Kathy Zucker, the condo president, said she had three children under the age of 6.

"They are going a little stir crazy," she said, "but they are hanging in there."

P.J. Molski, a 25-year-old graphic designer, said his place is dry. But he left his car on a street that flooded, and now it won’t start.

Almost every basement apartment he has seen in the small city is flooded, he said.

"There are just pumps going all over the city of people trying to get the water out of their basement apartments," he said.