From the BBC:
Carrots cause Swedish bomb scare
The carrot bombs had been placed around the city at the request of a local art gallery, as part of an open-air arts festival. They had only been in place for an hour before police received their first call. ...
Mr Blom described it as a harmless stunt. "After all, it is just carrots with an alarm clock and nothing else... this is just a caricature of a bomb," he said.