The accident took place at 16:00, creating serious traffic problems as the bridge lies on a main access route on the city's east.
Three years ago, the City of Kavala had performed small-scale maintenance work on the bridge's expansion joints but no urgent issues were found at the time. The City's technical services said the bridge deck might have collapsed under the weight of the passing crane truck.
Macedonia-Thrace Deputy Minister Katerina Notopoulou will be paying a visit to the area with a team of engineers on Saturday, while the Infrastructure and Transport minister has ordered state officials to inspect the bridge.
It is the second time a bridge collapses in East Macedonia and Thrace, following one at Kompsatos near Xanthi. "Either there is a shortfall in maintenance, which municipalities and regions are responsible for, or there are serious construction errors," Notopoulou said.