The University of Maryland, Baltimore and numerous downtown businesses closed early Monday, citing concerns about potentially violent activity in the area. Lexington Market, a city courthouse and businesses including T. Rowe Price and Venable LLP said police warned them of large gatherings and protests downtown. According to widely circulated flier, a high school "purge" was to take place at 3 p.m., starting at Mondawmin and ending downtown. Such memes have been known to circulate regularly, but today's has led to bolstered police presence around the city. The flier includes an image of protesters smashing the windshield of a police car...