Athletes and spectators at this week's Penn Relays will see heightened security in response to the bombings at the Boston Marathon.
The annual track meet draws hundreds of competitors of all ages and thousands and spectators to Franklin Field in University City.
Security has been tight at the famed event since the Sept. 11 terrorist attacks, with bag searches, magnetic wanding and pat-downs.
After the recent Boston Marathon bombings security is even tighter. Thursday morning K-9 units patrolled outside the stadium and rules will be in place about what can and can't enter Franklin Field.
The Penn Relays run through Saturday. The three-day meet at the University of Pennsylvania's Franklin Field attracts more than 15,000 participants from high schools, colleges and track clubs throughout the U.S. and beyond even drawing mega stars like two-time Olympic 10--meter gold medlist Usain Bolt in recent years.
It is the country's oldest and largest track and field competition.