Meanwhile, Miami police are ramping up security with a network of more than 20 surveillance cameras monitored in real time. "We have street-level cameras watching the actual boulevard and we have overwatch cameras giving us a bird's-eye view of the event," said Lt. Alex Gutierrez of the Miami Police Department.

Kim Hills, with the Miami Downtown Development Authority, said avoiding Biscayne Boulevard is key and closures there will cause a ripple effect through the downtown area.