DAYTONA BEACH, Fla. -- A blanket of haze lays over South Florida, shrouding the area in a thin layer of smoke. The smell of brush fires lingers in the air and that means trouble for those who have trouble breathing.

Broward's Air Quality and Health departments have issued a health advisory warning those at risk groups this could be a bad day.

Relentless wildfires are burning across Florida's Atlantic coast, taxing firefighters and overwhelming residents trying to save their homes with garden hoses.

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Firefighters in the Brevard County town of Palm Bay have spent more than 48 hours battling the state's biggest blaze, which has damaged about 70 homes and scorched 3,500 acres, or about 5 1/2 square miles.

Just south of Palm Bay, a 3,000-acre blaze destroyed at least four homes in nearby Malabar.

"I think it's sick. They created hell and they'll burn in hell," said one resident after hearing one of the fires may have been set by an arsonist.

Firefighters are working around the clock in alternating shifts to keep the flames under control.

Officials said they're worried about flare-ups that popped up overnight. Flare-ups when humidity is higher can be a bad sign because fire spreads even more quickly during the drier and windier daylight hours.

Today classes are cancelled for all students in Palm Bay because the flames are just too close.

Closer to home, conditions are perfect for a brush fire. A fire burning near the Sawgrass Expressway could make for some smoky skies in South Florida today.

Gov. Declares State Of Emergency

On Monday, Gov. Charlie Crist declared a state of emergency Monday as dry, windy weather fueled several wildfires on Florida's central Atlantic coast.

At least three homes were destroyed and hundreds of residents were under evacuation orders, but no injuries were reported.

The largest fire was in Malabar, where about 3,000 acres burned and at least two homes have been destroyed. In nearby Palm Bay, another fire claimed one home and students at two schools were released early as a precaution.

About 80 miles north in Daytona Beach, an 800-acre fire led to an evacuation order for about 500 homes. No structures were reported damaged, though officials warned that embers could fly more than a mile from the blaze and spark new hot spots.

The state of emergency allows Florida to use federal funds and the National Guard. The declaration also brings local emergency workers under state control and allows Florida to call on other states for help, if necessary.

More than 100 firefighters worked the blazes, cutting lines around the perimeter of the fires and dropping water from a helicopter.

The Florida Highway Patrol shut down a 7-mile stretch of Interstate 95 in Brevard County around rush hour Monday. U.S. Highway 1 was also closed in that area, and it was not known when it would reopen, FHP spokeswoman Kim Miller said.

"The fires have picked up in Malabar, so it's just heavy, thick black smoke and it's right at driver level," Miller said.

Authorities said one person may be responsible for the Malabar fire. An eyewitness saw someone in a car drop something into an open field, and the fire started shortly afterward, said Ernie Dieble, an arson investigator with the Palm Bay Police Department.

In Daytona Beach, a 5-mile stretch of LPGA Boulevard was shut down because the fire was too close to the road.

Firefighters also contained two smaller blazes near Cocoa that damaged four homes and two commercial structures, officials said.

In southwest Florida, authorities closed a stretch of State Road 776 near Charlotte County Sports Park because of a brush fire.