[blogblogginaway]

"A bomb squad detonated explosives found at the site of the blast"

According to PhiKapMom who was at the event, 2 men ran into the staduim immediately after the blast. Could be they either didn't have the devices in place or panicked and dropped them and ran. Just speculation on my part.

[hoboken109]

or 2 guys hearing the blast and running away from it .