BRIDGEPORT -- An investigation into a string of of Christmas Eve fires at vacant houses continued Wednesday, with evidence collected from the scenes and sent to the State Fire Marshal's lab for analysis, officials said.

Meanwhile the identity of a man whose body was found inside one of the burned-out building remains pending until an autopsy later this week, said William Kaempffer, spokesman for the city police and fire departments.

"This isn't one of those cases where we know who it is and are waiting to release the name once family is notified,'' he said. The man is a suspected squatter, but whether he died in the fire or had already been dead is something else that the medical examiner will have to determine, officials said.

The man's body was found inside a vacant house on Madison Court. Kaempffer said that he couldn't comment on a report that a gas can was found near the scene.

All of the fires are being treated as suspicious, Kaempffer said, and an investigation is continuing.

Firefighters were called back to two of the scenes Tuesday morning when the blazes rekindled and they continued to battle an industrial fire for a second day.

"We're on edge because whoever is doing this is still out there," Assistant Fire Chief William Hathaway said Tuesday. "We need to get it stopped immediately."

Hathaway said two firefighters received minor injuries during what proved to be an unusually busy Christmas Eve, beginning with a predawn fire in a woodworking factory at 33 Knowlton St.

Firefighters didn't leave that scene until 8 p.m. Tuesday, said Battalion Chief Robert Morton.

Hathaway said one firefighter was injured at the Knowlton fire and another was hurt at a blaze at a vacant house at 359 Olive St. in the Hollow neighborhood, one of the city's poorest and most densely populated.

Both firefighters were treated at a local hospital.

The Olive Street blaze was reported at 1:45 p.m. and was followed by a string of similar fires in nearby vacant houses, first at 325 Center St. just after 2 p.m. and then at 6 Madison Court shortly after 3 p.m.

While firefighters were attempting to extinguish the Madison Court fire, the Olive Street house went up again. A department spokesman said it was believed to have been "relighted" instead of rekindled.

At 9:34 p.m. Monday, firefighters were back in the Hollow, working a fire in a vacant house at 55 George St. At different times Tuesday morning, the Center and George Street houses were ablaze again. Both were contained.

Hathaway said all of the fires advanced quickly, which could indicate that an accelerant was used to start them. There is no evidence to suggest the factory fire is linked to the others, officials said.

The Fire Department, Police Department and State Fire Marshal's office are investigating the blazes.

"This has really stressed our resources," Kaempffer said, adding that a strike team with four fire trucks and one ladder truck from neighboring towns was called in to help.

Assistance came from the Stratford, Fairfield, Easton, Shelton and Trumbull fire departments.

The Hollow neighborhood, northwest of downtown and near the center of Bridgeport, has one of the highest crime rates and is home to a number of abandoned and blighted properties, many of them multifamily houses built close together.

The fires occurred as news spread of four firefighters being shot, two of them fatally, on Christmas Eve in a suburb of Rochester, N.Y., by a man who had set a house and car on fire in his neighborhood to draw them in. On Tuesday, an official in Webster, N.Y., said the gunman, who took his own life, left behind a long note in which he indicated he planned to kill people.

Anyone with information about the Bridgeport fires is asked to contact investigators at 203-581-5201.