Strong storms swept through the Pittsburgh area on Tuesday evening, prompting tornado and severe thunderstorm warnings. The storms left behind a trail of damage, knocking out power to tens of thousands of people.

ST. LOUIS — An elementary school south of St. Louis was damaged by a possible tornado as severe storms rolled through the region on Tuesday. The storm caused damage to Potosi Elementary School and left debris from a nearby building on the school’s parking lot.

Millions in the Upper Midwest face the possibility of a severe thunderstorm outbreak Monday—the start of several days of extreme weather threats across the country this week.