Shortly after several explosions occurred at the finish line of the Boston Marathon, Secret Service shut down Pennsylvania Avenue outside the White House, cordoning off the area with yellow police tape.

Several Secret Service patrol cars also blocked off the entry points to the road, and the security perimeter at the White House has been expanded.

Secret Service spokesman Ed Donovan says the measure was taken “out of an abundance of caution.” He says it is not unusual to expand or contract the security perimeters.

Source: CBS News – Secret Service Shuts Down Pennsylvania Avenue After Boston Marathon Explosion