In the aftermath of the bombing at the Boston Marathon, sports arenas across the nation are beefing up security.
The Los Angeles Police Department has added extra patrols at Dodger's Stadium.
"Chief Charlie Beck said Monday that his department would increase officer deployments at sporting events for the foreseeable future beginning with the Dodgers-San Diego Padres baseball game Monday evening."
More than 1,000 miles away at Marlins Park in Florida, a police officer with a German shepherd patrolled the entrance to the stadium where Miami hosted the Washington Nationals for Monday evening's baseball game.
In Baltimore, police said fans might see "tactical officers" deployed outside the stadium for Tuesday night's game between the Orioles and Tampa Bay Rays.
Fans heading in to watch the basketball game between the Washington Wizards and Brooklyn Nets in New York waited in long lines as security used wands to check individuals and bags.
Back in Boston, the National Hockey League game between the Bruins and Ottawa Senators was postponed and the NBA game between the Celtics and Pacers has been cancelled.