Spain's worst wave of wildfires on record spread to the southern slopes of the Picos de Europa mountains on Monday and prompted authorities to close part of the popular Camino de Santiago pilgrimage route.

Spain's weather agency warned the public on Monday to be "cautious" of the "very high or extreme fire danger."

France sent two teams of 100 firefighters, who were “currently arriving,” Virginia Barcones Sanz, the director general of civil protection and emergencies in Spain, told reporters on Monday. Germany is deploying a team of 66 firefighters with 21 vehicles, while Finland is sending 30 firefighters, she said.