Baltimore's controversial curfew law, the strictest in the nation, took effect Friday night with the aim of protecting children. The curfew requires those 13 and younger to be indoors by 9. Those 14 to 16 can stay out until 10 p.m. on school nights and 11 p.m. over the summer and on weekends.

ABOVE: Police patrol a residential neighborhood in east Baltimore minutes after the curfew law took effect.