A wildfire spurred by hot summer winds reached France's second-largest city Tuesday, grounding all flights to and from Marseille, injuring at least nine people and forcing many residents to evacuate or barricade themselves indoors as smoke choked the Mediterranean air.

A large hospital in the city switched to generator power, train traffic was halted in most of the surrounding area, and some roads were closed, while others were tangled with logjams.

More than 1,000 firefighters were deployed to tackle the fire, which broke out near the town of Les Pennes-Mirabeau before racing toward Marseille. Some 720 hectares were hit by the blaze, officials said in a statement Tuesday evening.

Nine firefighters were injured, according to the statement from the local administration, known as the prefecture. No deaths have been reported.

In its statement, the prefecture noted that "the situation is under control," though it said the fire, which was described as "particularly virulent," has not yet been extinguished.

Heat wave heightened wildfire risk

It came on a cloudless, windy day after a lengthy heat wave across Europe left the area parched and at heightened risk for wildfires. Several have broken out in southern France in recent days.

Light grey smoke gave the sky over Marseille's old port a dusty aspect as water-dropping planes tried to extinguish the fire in the outskirts of the city, which has a population of about 900,000.

Hundreds of homes were evacuated. The prefecture urged people in the affected areas to stay indoors and off the roads. With the fire approaching Marseille, the prefecture also advised residents in the north of the city to keep windows closed to prevent toxic smoke from entering their homes.

One distressed family watched the smoke over their neighbourhood in the hills above the port city and showed the Associated Press how the roof of their neighbour's house had been damaged in the fire as they worried about their own.

The airport in Marseille announced that the runway had been closed at around midday. The prefecture said train traffic was halted, notably after a fire neared the tracks in L'Estaque, a picturesque neighbourhood.

As a safety measure, the city's Hospital Nord switched to generators "due to micro power cuts."

"The aim is to secure the imaging sector. We are not worried as we have a high level of autonomy," the University Hospitals of Marseille said, adding that because of the disrupted traffic it was asking workers to remain at their posts until the next shifts started.