Earlier today, the Tower and Tracon at KCVG had to be evacuated because of a "fire alarm" shortly before 4PM EDT. Indianapolis Center had to take over for the Cincinatti Tracon and all flights into and out of KCVG had to use Uncontrolled Airport procedures and communicated on Unicom/CTAF 122.95. Numerous inbound flights were placed in holding patterns. The Tracon came back in service about an hour and a half later but the Tower, for whatever reason, remained closed for about another two hours. The tower reopened just before 730PM EDT, about three and a half hours after the initial evacuation. The attached audio is a mix of tower, ground and Indianapolis Center.