Swiss police ordered the evacuation of several mountain villages late Monday as a forest fire spread, and it was not clear how many people were injured.

Around 200 firefighters, the army, police and other agencies joined helicopters in fighting the blaze in the canton of Valais throughout Monday afternoon, but the blaze continues to burn.

The fire is spreading towards Ried-Morel-Riederhorn,” police said in a statement on Twitter, saying they would evacuate the village of Ried-Morel, near the town of Brig, which is close to the Italian border. He later added that three more villages were to be evacuated and warned of rock falls.

Air Zermatt, which operates four of the helicopters, said efforts to extinguish the fire would continue through the night. Valletta police released pictures showing a helicopter dropping water over a forest fire in the afternoon. A later shot showed a much larger fire with smoke covering most of the forest.

The region is being affected by the same Mediterranean heat wave that is affecting southern Europe, with temperatures topping 30C in parts of the canton of Valais this week, according to forecasts from the weather service.