Camden officials and residents continue to seek an explanation for a string of fires that erupted over the Fourth of July weekend - all within a one-mile radius.

Firefighters responded to 14 fires from Saturday through Monday. Thirteen of those considered "suspicious" took place in vacant homes and are under investigation as arson, said Camden Fire Department Chief Michael Harper.

"We haven't had anything like this in a number of years," he said. "We're all scratching our heads about this. All of a sudden this took place; it's really strange and unusual."

The four fires on Saturday, nine on Sunday and one Monday resulted in about 18 properties damaged, said Camden County Police Capt. Greg Carlin.

Officials have not made any arrests, and the Camden County Police Department will continue to seek leads through a 24-hour tip line, surveillance videos, and dialogue with residents, he said.

It appears that several of the fires were ignited from the backs of the buildings, Carlin said.

Investigators are looking for suspects by sifting through public and private surveillance videos from surrounding streets.

The fire department brought in help over the weekend from several surrounding towns, including Gloucester City and Pennsauken, Harper said.

Seven firefighters - four on Saturday and three on Sunday - were sent to the hospital as a result of battling the flames. Injuries included heat exhaustion, smoke inhalation and a dislocated thumb. All firefighters were released by Monday, Harper said.

"It's hard to tell whether it's one person," Harper said. "Some of them are so close together as far as timing. It's difficult to put a finger on it."

Officials established an arson task force Saturday, pooling efforts from the county Fire Marshal's office, the Camden County Prosecutor's Arson Unit, the Camden County Police Department, as well as the state fire marshal's office.

"This is very serious," Carlin said. "We try to plan for everything and strategize to plan for any crime. This is thankfully not a frequent event for us, and we're hoping with the community's help we can get this resolved."

Matthew McMillian, 55, lives between the two properties on Haddon Avenue that went up in flames Sunday. Sitting on his front porch Tuesday afternoon, McMillian said the fires seemed like a mystery and worry him.

"All I heard was the fire trucks; I came out of the house to see what was going on," said McMillian, who has lived in the area for seven years. "I was wondering why there were a lot of them. I don't know why anybody would do that."

Markee Boyer, 40, who also lives between the two Haddon Avenue fires, echoed McMillian, saying the sirens made him curious about what was going on.

"It's really crazy," Boyer said. "I'm surprised they didn't catch anybody since it was the daytime."

Carlin said officials are going through vacant alleys and properties to make sure no one is occupying them. The city's public works department will work to ensure the dozens of vacant city homes are boarded up to prevent entry.

Neighbor Diana Rivera, 42, said the abandoned properties on Walnut Avenue - including one that was set on fire - tend to have people rummaging around them even though they are boarded up.

"We were just afraid that someone might set this house on fire," she said Tuesday at her residence.

Rivera said she wished she had surveillance cameras on her block to try to help figure out who was responsible for the fires and prevent them from happening again.

"Maybe it's just somebody who wants some attention," Rivera said, "but they're doing too much."

Officials encouraged anyone with information about the fires to call the police department's 24-hour tip line at 856-757-7042.