Unidentified persons damaged the windowpanes of two air-conditioned buses operated by the Shiromani Gurdwara Parbandhak Committee (SGPC) to ferry devotees on the Heritage Street were last night.Condemning the incident, the Sikh body sought action against those responsible.The incident reportedly took place between 2 am and 2.30 am when the buses were parked on the Heritage Street.Four windowpanes of one bus and two of the other were found damaged.The buses are operated by the SGPC to provide transport facilities to devotees visiting Harmandir Sahib from different parts of the country and abroad and to facilitate their visits to various gurdwaras.SGPC president Advocate Harjinder Singh Dhami termed the incident painful and unfortunate.Dhami said the SGPC was also conducting an inquiry into the incident at its own level. He urged the police administration to take the matter seriously, investigate the incident and take strict action against those responsible to prevent such incidents in future.