MARDAN - Two persons, including a constable, were killed while seven others, including three constables, got seriously injured when an explosive device went off in Par Hoti area early in the morning, sources said. They said the locals informed police that militants had planted explosive devices in the Government Girls High School, Shahdad Baba, in the limits of Par Hoti Police Station. Sources said the police personnel on duty in the area came to the spot and started searching the explosives at 6:45 am. They said the explosive devices, hidden in a rubbish heap near the school gate, went off killing constable Allah Nawaz, resident of Khairabad, and a passer-by, identified as Tahir Khan, son of Shabir Shah, resident of Shahdand Baba, on the spot. They said constables Atif, resident of Gharo Shah, Jawad, resident of Baghcha Dheri, and Ali Bahadur, resident of Katlang, got seriously injured. They added that watchman of the school and other persons got seriously injured. The injured were shifted to District Headquarters Hospital, where their condition was stated to be out of danger. They said the school gate and boundary wall were partially damaged. The sources further said that the bomb disposal squad officials came to the spot and defused another explosive device at the site. Following the incident, the police launched a search operation, but no arrest was made till the filing of this report. Police registered a case against unidentified militants. Sources said that militants set up their strongholds in different parts of the city and they started their activities. They said the intensification of militant activities in the district, particularly in the city, created panic among the masses.