JERSEY CITY -- A three-alarm fire near the Hudson County Administration Building damaged four buildings, displaced some 20 residents and sent a Hudson County Sheriff's officer and a firefighter the hospital Thursday.

Firefighters responding to the 3:36 p.m. blaze found a fire that started on the top floors and roofs of 629 and 631 Newark Avenue -- a pair of attached three-story buildings that also house a meat market and a Domino's pizza.

Hudson County Sheriff's Officer Azmi Tosca was in front of the Administration Building at Newark and Oakland avenues at 3:34 p.m. when he saw the smoke and called headquarters asking for backup and notification of the fire department.

With other officers from the Sheriff's department and one from the Hudson County Prosecutor's Office, they raced into Domino's, into the backyard through the kitchen and climbed the fire escape to the roof, Hudson County Sheriff Frank Schillari said.

They found a man who had just emerged and helped him to safety. Officer Thomas DeStasio suffered facial burns from the heat and smoke inhalation during the effort. Officers also rushed into the floors above Moloney's Market and helped a woman and child out of the building, the sheriff said.

A firefighter also suffered facial burns.

In all, the building at the corner of Newark Avenue and three attached buildings on Newark Avenue suffered various degrees of to there upper portions, with 629 and 631 Newark Ave. suffering the most damage to their upper floor and roofs, Jersey City Fire Department Chief Steve McGill said.

The cause of the fire is currently under investigation.

Tom Moloney, the fourth-generation operator of the meat market founded in 1875, said he didn't see or smell anything, but sheriff's officers rushed in and said "Your building's on fire." He said he rushed upstairs with sheriff's officers before clearing out of the building at 627 Newark Avenue.

"It's not a good feeling," said Moloney, standing amid the fire trucks, water puddles and tangle of hoses. "I just renovated the whole building down to the studs three years ago."

But the meat and poultry purveyor said he believes he will be able to reopen in the morning.

The sheriff said: "I'm very proud of my officers who disregarded their own safety to make sure the victims were evacuated."