MILAN (AP) — News reports say thieves attempting to rob a jewelry store in Venice's famous St. Mark's Square set off panic among tourists when they ignited smoke bombs to cover their movements.

The news agency ANSA says one smoke bomb was set off Friday near St. Mark's Basilica bell tower, and another in the middle of the famed colonnaded square. Panic ensued, the news agency reported, as tourists and merchants suspected either a fire or a possible attack.

The Gazzettino daily reported that a tourist seated at an outdoor cafe table saw one person set off a smoke bomb and two others trying to enter a jewelry store and alerted police. The would-be robbers disappeared into the crowd.

Italian police declined to confirm details about the incident, saying it was under investigation.