The five told rescuers that they have survived on food and water on the bottom level of what had been the three-story grocery store.
Sixteen members of the team are cutting through concrete blocks to reach five, who have been speaking with the rescuers.
The team of 80 specialists are on a search-and-rescue mission through the wrecked mass of concrete and metal in Haiti's earthquake-ravaged capital, using technology that has been improved since the Sept. 11 attacks.
The squad touched down in Port-au-Prince on Saturday after a two-day wait for clearance to land at the destroyed city's overloaded airport.
Deputy police inspector Robert Lukach, who serves in the New York Police Department's elite Emergency Services Unit, said he's more optimistic about finding survivors in Haiti than he was at ground zero.
"That quickly became a recovery mission. But this is still a rescue mission, and we are hoping for the best," he said.
He said that even days after the quake, he is hopeful there are pockets in the rubble where people may still be alive, although the crew was worried they would arrive too late, after too much waiting around.
The team, which plans to spend at least a week in Haiti, is one of 28 federal urban search and rescue teams around the United States that can mobilize during a disaster.
They are bringing three tractor-trailers full of equipment, including sound gear to listen for survivors trapped below wreckage, cutting tools that can smash through concrete and shore up rubble as they burrow down, and rescue dogs.
"We can be more prepared for this because we're going in with more knowledge," Lukach said.
The cataclysmic earthquake rocked the impoverished island nation Tuesday. The Red Cross estimates that 45,000 to 50,000 people were killed. As humanitarian aid and troops have arrived from around the globe, the focus has already begun to shift to getting aid to survivors.
Downey's father, Ray Downey, died in the line of duty on Sept. 11. He was the former head of the fire department's Special Operations Command and a renowned expert in search-and-rescue and building collapses.
Downey has followed in his dad's footsteps as a special operations battalion chief. When he dug through the rubble in Haiti after Gustav hit in 2008, the collapsed buildings were mostly wood-frame, rather than concrete, he said, which made it easier to find people living in air pockets below the wrecked buildings.
"As each day passes . . . it gets more difficult to find survivors," Downey said. "But they've had plenty of collapses in this country, and people have lived seven to 10 days, and even longer. We're hopeful."
The team, made of 40 NYPD officers and 40 from the fire department, receives extensive training in structural collapse, concrete collapses and trench rescues, as well as high-angle and water rescues. They regularly deal with structural collapses in New York.
"We are to some degree used to this," said Lukach. "We respond to small-scale disasters all the time."
The team hit the ground in Port-au-Prince with enough food, water and masks to keep them sustained for 72 hours as they work down into the mass of rubble.
Downey said they were also arriving with hope.
"We gotta get to work," he said.