A fast-moving wildfire fanned by gale-force winds has been raging on the outskirts of France’s second-largest city, Marseille, officials said, as firefighters around the Mediterranean battle blazes sparked by an intense heatwave.

“The fire is on the fringes of Marseille,” the regional prefect, Georges-François Leclerc, told reporters on Tuesday, adding that the blaze was not yet stable or contained, but the situation appeared to be “under control”.

“The instructions are simple: have confidence in firefighters, let emergency services do their job, and stay indoors,” he said. “Firefighters are defending the city.” France’s interior minister, Bruno Retailleau, was due to arrive in the city during the evening.

Fanned by a 70km/h wind, with gusts reaching 100km/h, the fire filled downtown Marseille with acrid smoke and flying cinders. Videos from the central Old Port area showed large plumes of smoke billowing over the city. About 450 people were evacuated, Marseille city hall said.

It urged residents, especially in the northern 15th and 16th arrondissements, closest to the blaze, to “stay inside so as to avoid any exposure to smoke” from the fire. Four sports halls in the city were opened to accommodate any more evacuees.

“You can feel it, you can see it and you can smell it,” Vanessa, a 16th arrondissement resident, told BFMTV. “It’s horrific. We’re all frightened. It’s a catastrophe, you can’t even put your nose outside the front door – in Marseille!”

Marseille airport cancelled all flights, train services to and from the north and north-west of the city were suspended, two motorways, main roads and several road tunnels in the city were closed, and many bus services halted, authorities said.

map of the Marseille area

The prefecture of the Provence-Alpes-Côtes d’Azur region issued multiple mobile phone alerts urging inhabitants to also close their doors and shutters, hang wet laundry around openings, and keep all roads clear for emergency services.

City hall said 720 firefighters, including dozens from neighbouring departments, were battling the blaze with 220 emergency vehicles, helped by helicopters and water-bombing planes. About 350 hectares of land had been consumed by late afternoon.

Local authorities said 20 houses had been destroyed, including several within the city limits. Nine firefighters were being treated for smoke inhalation and four residents had been hospitalised in “relatively urgent” circumstances.

The mayor of Marseille, Benoît Payan, congratulated the city’s firefighters “who have so far saved several hundred houses”. A major hospital to the north of the city had switched to emergency generators “as a precaution” but was safe, he added.

“As we speak, it’s a battle,” Payan said, likening tackling the wildfire to “guerrilla warfare”.

He added: “We’re waiting to see what happens overnight, because that’s critical too. Everything is strategic: wind speed, humidity, nightfall … It’s extremely complex.”

Marseille airport suspended all flights at midday, shortly after the blaze erupted outside the nearby town of Les Pennes-Mirabeau. Local media reported the cause appeared to have been a vehicle that caught fire on the A552 motorway.

Departures to Brussels, Munich and Naples were cancelled, with incoming flights diverted to nearby airports, including Nice and Nimes. Marseille is France’s second largest regional airport, handling nearly 11 million passengers last year.

Police try to extinguish a blazing car in the L’Estaque district of Marseille on Tuesday. Photograph: Clement Mahoudeau/AFP/Getty Images

There were no immediate reports of casualties but the mayor of Les Pennes-Mirabeau said two housing estates had been evacuated and firefighters were preparing to fight off approaching flames near a retirement home.

Three southern French departments, Bouches-du-Rhône, Var and Vaucluse, are on red fire alert. Many of the region’s forests have been closed and barbecues and cigarettes banned near wooded areas.

About 4,000 fires start each year in France, about 90% caused by human activity. Negligently or accidentally causing a wildfire carries a jail term of up to 10 years.

The wildfire approaches the L’Estaque. Photograph: Clement Mahoudeau/AFP/Getty Images

About 250km west of Marseille, a wildfire that started near the city of Narbonne was still active on Tuesday after burning through about 2,000 hectares of forest, forcing the partial closure of the A9 motorway and dozens of evacuations.

Fuelled by 60km/h winds, the blaze was still advancing but “more moderately”, the prefect of Aude department, Christian Pouget, said on Tuesday. More than 1,000 firefighters had been deployed, five of whom had been slightly injured. Between 4,000 and 5,000 Narbonne residents were still confined to their homes, he said.

A helicopter combats a forest fire near Tarragona, Spain. Photograph: José Jordan/AFP/Getty Images

In Spain, firefighters in the north-east of the country continued to battle a wildfire in the Catalan province of Tarragona that has burned through more than 3,100 hectares of forest, farm and urban land, and confined 18,000 people indoors.

Winds of up to 90km/h were complicating the efforts of about 100 troops from Spain’s military emergencies unit and 300 regional firefighters to combat the fire, which broke out in the municipality on Sunday.

Syria on Tuesday appealed for help from the EU in battling wildfires that have been blazing for six days, sweeping through a vast expanse of forest. Neighbouring Jordan, Lebanon and Turkey have already dispatched firefighting teams to assist.

Forest fires ravaging Syria’s Latakia province on Monday. Photograph: Anadolu/Getty Images

The UN’s office for the coordination of humanitarian affairs in Syria said the fires had affected about 5,000 people and 60 communities, destroying 100 sq km of forest and farmland – more than 3% of Syria’s forest cover.

Rugged terrain, the absence of firebreaks, strong winds and the presence of mines and unexploded ordnance were making it difficult to combat the fire effectively, the minister for emergencies and disaster management, Raed al-Saleh, said.

In Greece, authorities in Athens shut the Acropolis, the city’s most visited ancient site, from 1-5pm local time as temperatures soared to 38C. The ruins are on a rocky hillside that offers little shade.