MADRID (AP) — Spaniards were rushing to buy specialized glasses to view a rare total solar eclipse Wednesday, as authorities warned people flocking to rural areas to avoid anything that could spark new wildfires.

Across a swath of northern and central Spain, millions of people will have some of mainland Europe’s best views of the celestial spectacle. It will begin around sunset, when the sun, moon and Earth align, briefly bringing parts of the Iberian Peninsula — plus slivers of Greenland and Iceland — into darkness.

The event could draw at least an additional half a million visitors, Spanish authorities say. Against the backdrop of scorching summer temperatures and wildfires, officials have rolled out a large public safety campaign ahead of the much-anticipated eclipse, with totality — when the moon completely covers the sun’s light — expected to last less than 2 1/2 minutes.

Spanish authorities prepare for influx of visitors in rural areas

Spain’s Interior Ministry said 350 official viewing sites have been set up across the country’s sparsely populated interior, an area often referred to as “Empty Spain.” Authorities have limited or restricted access to another 123 sites because of environmental conditions or obstacles that could hinder an evacuation in the event of a wildfire.

Only weeks ago, the most destructive wildfire in Spanish history devoured 500 square kilometers (193 square miles) and forced the evacuation of tens of thousands of people in central Spain. Several smaller wildfires remain active elsewhere in the country.

More than 33,500 law enforcement officers will be deployed to observation areas and access points, the ministry said.

“High temperatures, the accumulated dryness of vegetation, and the intense pressure on natural areas due to projected travel necessitate extreme preventive measures,” Interior Minister Fernando Grande-Marlaska said.

Much of Spain will be on alert Wednesday as temperatures climb above 35 Celsius (95 Fahrenheit) and vegetation remains bone-dry. The national weather agency, AEMET, forecast such temperatures across northwest to southeastern Spain, including many areas where the total eclipse will be observed.

Authorities’ top priority is to prevent even a single spark that could lead to a fire, as happened in Ávila, west of Madrid, in late July. They are urging visitors not to light fires, litter or park in areas with dry vegetation.

Eclipse glasses are going fast

Special eclipse glasses are essential for safe viewing, even if only a sliver of the sun remains visible.