Hundreds of reinforcements were sent early Tuesday to battle the fire, progressing at a slow but steady pace through the ravaged Maures hills, where massive forest fires in July had already claimed four lives.

"There are now 1,600 men on the scene and we are expecting 400 more to arrive during the morning," local fire chief Lieutenant-Colonel Jacques Baudot told AFP.

A fleet of 25 water-dropping aircraft were deployed to help firefighters put out the blaze, previously split on two fronts but now just a solid wall of fire burning near the town of Cogolin, west of the Riviera resort of Saint-Tropez.

The three firemen killed late Monday were burned alive in their truck, which was suddenly encircled by flames whipped up by the swirling Mistral winds.

Three other firemen in a second truck that was also trapped in the flames managed to escape, officials said.

Some 4,500 hectares (11,000 acres) have thus far been consumed by the latest blazes in the Maures hills, where four people were killed in July in fires amid a heat wave and the worst drought in southern France in a quarter of a century.

The dead firefighters -- aged 37, 42 and 43 -- were all married and had seven children among them, aged one to 12. The rest of their brigade was removed from duty and was receiving psychological counseling, Baudot said.

President Jacques Chirac expressed "deep sadness" over the deaths, hailing the courage of the "thousands of volunteers and professionals who have fought day and night for the last three months against the fires devastating the south of France and Corsica -- too many of them started deliberately".

Prime Minister Jean-Pierre Raffarin and Interior Minister Nicolas Sarkozy also sent their condolences to the victims' families.

Since Sunday, about a dozen other firefighters have suffered burns or other injuries fighting the fierce flames.

Rescue workers have evacuated 40 families from the town of La Garde-Freinet, as well as several campsites and a vacation resort in the Maures hills.

Three helicopters and a boat were standing ready to evacuate firemen and civilians, and a team of psychologists were on hand to help trauma victims, officials said.

Regional authorities announced that the resumption of classes following the summer break had been postponed in seven towns around the Gulf of Saint Tropez.

Public prosecutors said they had launched a preliminary inquiry to determine the cause of the fire.

Wildfires also continued to blaze out of control Tuesday in Corsica, authorities said, with Cap Corse, the northernmost tip of the French Mediterranean island, the most at risk.

Some 800 firefighters backed by nine water-carrying aircraft struggled to rein in the fires on the island, with officials saying they were on the verge of bringing them under control.

One person died in July in Corsica's fires, bringing the death toll from France's summer fires to eight.

Sarkozy, during a visit to fire-hit areas in southern France on Monday, said a total of 54,000 hectares of woodlands had been destroyed across the country thus far this year -- the worst total in 15 years.

TERRA.WIRE