Brevard County firefighters battle a house fire in Malabar, Fla., early Monday. The house was destroyed by the brush fires in the area. (Craig Rubadoux/Florida Today/Associated Press)

Dry conditions and scorching heat fuelled wildfires Tuesday in north and central Florida, where hundreds of homes have already been damaged and thousands of people warned to be prepared to evacuate.

Florida's governor, Charlie Crist, has declared a state of emergency covering the worst of the fires around Daytona Beach and along the dried-up shores of Lake Okeechobee. The fires began late last week.

The biggest blaze is near the town of Palm Bay in northeastern Florida, where more than 1,400 hectares are on fire and at least 70 houses have been destroyed.

"Every time I turn around, another house is on fire," said Yvonne Martinez of Palm Bay municipality. "We don't have enough resources on our own to do a job like this."

Flare-ups spread the flames overnight Monday. A fresh outbreak of fire at night when atmospheric humidity is higher often means an even faster acceleration of the flames during the drier, hotter conditions in daytime.

Just south of Palm Bay, a 1,100-hectare blaze destroyed at least four homes in the village of Malabar, including the house that local resident Butch Vanfleet built in 1980 and tried in vain to protect with a garden hose.

"It's devastation," Vanfleet said, "All you can see is … ash in between the palm trees. The fire came so quickly we barely got out of there."

Arson possible: investigators

Authorities said the fire at Malabar may have been caused by arson. A witness saw someone in a car drop something into a open field shortly before the blaze began, an arson investigator said.

A resident wets down a roof Monday afternoon as brush fires surround homes in Malabar. (Craig Rubadoux/Florida Today/Associated Press)

Further south around the large and shallow Lake Okeechobee, a several hundred-hectare fire continued to blaze along the lakeshore. Local officials said a drought that caused a drop in lake levels had left piles of dead vegetation that was a perfect fuel for wildfires.

For two days, thick smoke from the Okeechobee fire has wafted west over the cities of Fort Myers and Naples, officials said, prompting fears of respiratory problems.

The governor's declaration of a state of emergency frees up extra funding to fight the fires, as well as allowing Florida to call on other states for help.

Several firefighters have been injured so far, officials said.

With files from the Associated Press