NPR News

Monday's explosions in Boston have led to heightened security elsewhere, with New York, Washington and Los Angeles among the cities taking action within hours of the blasts.

"We're stepping up security at hotels and other prominent locations in the city through deployment of the NYPD's critical response vehicles until more about the explosion is learned," Paul J. Browne, the deputy commissioner of the New York Police Department, .

Two explosions rocked the finish line of the Boston Marathon this afternoon, leaving at least three dead and dozens injured, the Boston Police Department reports.

The explosions happened in quick succession four hours after the beginning of the race, the world's oldest and one of the most prestigious road races in the world. At that point, the majority of 27,000 runners had crossed the finish line. Thousands, however, were still out on the course.