The Congress Mandalam Committee office at Karivellur in Kannur, Kerala, was vandalised late Sunday night. Unidentified persons broke into the office and set poll campaign flexboards on fire. The attack targeted Gandhi Mandiram, the office on Karivellur Theru road. The assailants broke the door lock to enter. The damage was discovered Monday morning by party workers. A complaint is filed with the Payyanur police, who have started a preliminary inspection. Congress sources said a night camp was held Sunday at the office for a special intensive revision programme, called by KPCC under the Mandalam committee's leadership. It is suspected the attack happened after workers left around midnight. This is not an isolated incident. Earlier, the Congress office at Mathattum in Kolassery, Kannur, was vandalised late Saturday night. Unknown people broke shutters, damaged property, and dumped party materials on a road and creek.