A fast-moving fire destroyed a vacant South Camden warehouse Saturday, injuring two firefighters but mostly sparing the adjacent block of rowhouses.

The eight-alarm fire was the second major Camden blaze in three days. Officials did not know the cause of either.

Saturday's fire erupted shortly before 2:30 a.m. at the Howland Croft building, a three-story former garment factory in the 400 block of Winslow Street, just off Broadway.

The building had been used to store building materials and computer monitors, Fire Chief Michael Harper said. It's in the Waterfront South section of the city, home to blocks of rowhouses and industrial sites including Camden County's sewage-treatment facility.

Firefighters reported the blaze was "one of the fastest-moving fires they'd seen," Harper said, but they cut it off before it did much damage to the homes on Winslow.

"They had to physically go in and extinguish those fires to save the homes, but they did," Harper said.

Companies from around the region fought the blaze, which was under control by 6 a.m.

Two Camden firefighters were treated at hospitals, Harper said - one for a sprained foot and the other for heat exhaustion.

About 30 residents were displaced, but most returned to their homes by 10 a.m.

Damage to two homes on the block was serious enough to keep occupants out for the night, said Camy Trinidad, executive director of the Camden County chapter of the American Red Cross.

One family stayed with relatives, and another was housed temporarily by the Red Cross, which was also coping with the fallout from Thursday's 12-alarm fire, which began in a vacant building formerly rented by the Reliable Tire Co. and which virtually leveled two blocks.

That blaze displaced dozens, Trinidad said, many still housed in a motel by the Red Cross, which was working with city officials to find permanent housing for them by Monday.

"It was," Trinidad said, "a tough couple of days."

Union officials had said the widespread damage from Thursday's fire was exacerbated by recent layoffs of Camden fire personnel.

Harper has rejected the argument that layoffs played a role in Thursday's response time.

The fire chief also said vandalized hydrants - a problem Thursday - were not a factor in Saturday's blaze.

On Saturday afternoon, neighbors gathered on Broadway and side streets, watching crews extinguish hot spots and cope with the aftermath of the fire.

Brothers Pedro and Juan Vega looked tired after being up most of the night. The two live in their family home on Winslow Street across from the factory.

"Barely anything was hurt" in their house, said Juan Vega, 26. "Just some windows broken, a little water damage."

The family was awakened shortly after 2 a.m. by "crackling. It was very loud," said Pedro Vega, 28. "The heat was unbearable. We couldn't get out through the front."

The brothers and their family escaped through the back door.

The Vegas said that while no one had worked in the Howland Croft building, it hadn't always been empty.

"Homeless people sleep there, and people take things from there - copper, whatever they can find," Juan Vega said.

Sitting on a chair in front of their home on Broadway, sisters-in-law Stephanie Culbreath and Terri Davis praised the work of the firefighters, but said they were eager for their electricity to be turned back on. Officials cut the power to a swath of the neighborhood about 4 a.m., they said.

More worrisome, they said, was the second fire in just a few days.

"I do think maybe it was set," Culbreath said. "It does seem they're targeting these old vacant warehouses. It's been vacant for years, and there was never a fire. It makes you wonder."

Another neighbor, who declined to give his name, agreed.

"Two in a couple days? It just doesn't sound right," the neighbor said.

Contact staff writer Kristen Graham at 215-854-5146 or kgraham@phillynews.com.