Wildfires in the southeastern U.S. state of Florida have forced hundreds of people to evacuate their homes and shut down a number of major roads.

Florida officials say the fires started Sunday and engulfed a combined area of nearly 11 square kilometers in two counties, Brevard and Volusia.

One fire in Brevard County covered more than eight square kilometers alone.

Officials say about 500 homes were under mandatory evacuations, while people in another 200 homes were asked to leave voluntarily.

The Florida Division of Forestry warns that windy and dry conditions are making it difficult to contain the fires.

At one point, the smoke from the fires was so thick it forced officials to shut down Interstate 95, a major north-south highway. That highway was reopened Monday.

Investigators think some of the fires may have been set intentionally.

Some information for this report was provided by AP.