CAMDEN, N.J. (WPVI) -- A firefighter was injured battling a two alarm blaze early Friday morning in Camden, New Jersey.
"They knocked on my door," said Camden resident Alfredo Villalobos.
That knock was from firefighters because the vacant building behind Villalobos' Camden home was on fire. He worried it would spread.
"I had to move everything out of my building - my truck, everything," he said.
Firefighters were called out to the 1100 block of Kaighn Avenue around 6:00 a.m. Friday and were met with heavy smoke and flames on the upper floors.
Viewer video showed firefighters battling the blaze. Initially firefighters went inside, but they pulled back when one firefighter was injured after his leg went through a floor.
"When the guy got hurt, we pulled him out," said Camden Fire Chief Michael Harper. "Then we did a defensive operation. We didn't have anyone in the building for awhile, and we tried to contain fire as best we could."
The firefighter was not seriously injured. He was treated for his injury at the scene.
Neighbors say Ralf's Plumbing used to operate out of the building. But like many buildings on this block it has been vacant for years and frequented by squatters.
"Empty building," said Chris Brown, who works nearby. "They had stripped all the copper and pipe out of it. Probably just sleeping in there trying to get warm.
The fire company is located down the block, and firefighters are aware squatters are in and out of the building that burned.
They've made themselves familiar with the property, and Chief Harper believes that helped them Friday morning.
"They had been doing some block checks recently and walked through the property because they had seen it as being problematic," he said.
The fire burned through the roof.
Firefighters had to go through and tear up the walls to make sure there was no fire inside them, so there is quite a bit of damage. The building was being boarded up.
There was also some damage to the building next door, mostly exterior damage.
Investigators are working to determine the cause.