Back at home, they're expecting 36,000 runners and possibly a million spectators tomorrow for the 108th running after last year's bombing there will be an extraordinary level of security. Brian Ross... See More
Back at home, they're expecting 36,000 runners and possibly a million spectators tomorrow for the 108th running after last year's bombing there will be an extraordinary level of security. Brian Ross will bring us a look inside the high-tech command center. What's new this year in terms of security? Well, good morning, dan, the new to the part of security is cameras installed from all along the parade route. These cameras will be monitored in an underground command center, called the bunker, this high-tech operation. This year, the goal is to make sure they can spot something before an attack actually takes place. There will be 4,000 police officers along the parade route. Looking for anything out of the ordinary. Spectators have told and asked not to bring backpacks. If they do bring them, they can expect a friendly tap on the shoulder. And possibly a search. What are officials most worried about? Well, the Boston police commissioner bill Evans told me yesterday his greatest fear is a copycat attack that would mirror what happened last year. They had a dry run on Tuesday during the memorial tribute, when a man was carrying a wac backpack, police took the backpack on the ground, detonated it. A huge day for Boston, logistically and psychologically tomorrow. We'll turn now to that big hit against Al Qaeda in Yemen,
This transcript has been automatically generated and may not be 100% accurate.