More than 1,000 firefighters battled wildfires in central Portugal on Monday, forcing the evacuation of villages and fluvial beaches as the authorities hoped to limit the number of residents at risk. 

So far 33 people have been injured, including one who is in serious condition and remains hospitalized with first- and second-degree burns.  

Portugal's Civil Protection said some houses were destroyed by the flames but did not give a specific number.  

Civil Protection said earlier on Monday that 90 percent of the wildfire was under control but warned that the remaining blazes required "a lot of attention" as the winds whipped up later in the day, fanning the flames in tinder-dry conditions.

Villagers, as well as local authorities in Macao and Vila de Rei, areas in the heart of the fire zone, said there were not enough firefighters and resources to combat the flames.

"The fire is out of control, without resources on the ground, and the population at risk," Macao Mayor Vasco Estrela told Portuguese radio station TSF on Sunday. "We never thought we would live through this again." 

Images broadcast by Portuguese TV channel TVI showed villagers in Macao trying to protect their houses and animals as smoke filled the air, forcing many to wear masks.

Covered in eucalyptus and pine trees, central Portugal is frequently hit by summer blazes, with hilly terrain making it especially difficult for firefighters to reach. 

The fires also stirred memories of a devastating wildfire in the central town of Pedrogao Grande in June 2017, the worst disaster in modern Portuguese history, which killed 64 people and injured more than 250. 

Internal administration minister Eduardo Cabrita said police had opened an investigation on the fires, adding that local authorities considered it unusual that all the blazes had started in a narrow time frame between 2:30 p.m. and 3:30 p.m. local time on Saturday in the same area. 

Portugal's judiciary police have collected some evidence and artifacts that could be related to the fires' origin.  

In a statement, police said that a 55-year-old man was detained on suspicion of starting a blaze in the Portuguese district of Castelo Branco, yet another police source added that the detention was not related to the ongoing fires.  

Spain announced late on Monday that it was sending two aircraft to help tackle the fires.

Data from the European Union fire mapping service showed about 8,500 hectares burnt over the weekend.