Wind-whipped fires leaped from rooftop to rooftop and charred thousands of acres across Brevard and Volusia counties in central Florida on Monday, destroying or damaging at least 51 homes and injuring at least four firefighters.

Gov. Charlie Crist declared a state of emergency.

The worst fires were in Palm Bay, where desperate residents fought to save their homes with water from garden hoses and swimming pools. Confused students screamed as firefighters evacuated them from a high school. Hundreds of residents were forced to flee their homes.

Authorities think that an arsonist or group of arsonists set as many as nine fires in Palm Bay, and that embers sparked the rest.

"It's just bad," said Yvonne Martinez, Palm Bay Police Department spokeswoman. "The wind is causing the fire to jump a half a mile at a time."

Major fires also burned in northern and southern Florida.

On Monday, early-morning humidity and mild temperatures had calmed central Florida's fires. But as the day wore on, the wind picked up and humidity plummeted.

The Palm Bay fires erupted within 18 hours Sunday, forming a ring around the city. Most began near roads.

"Somebody was very busy," said Palm Bay Fire Marshal Mike Couture.

A suspicious vehicle was seen in the area before Sunday's fires. There is a $10,000 reward for information leading to the capture of the suspect.

One Palm Bay firefighter was shocked by an electrical line and taken to a hospital, city officials said. Three other firefighters were injured, but no details were available.

Officers went door-to-door on the south side of Palm Bay, asking residents to grab what they could and leave immediately. If they refused, they were asked to provide names of their next of kin, Martinez said.