Unidentified persons opened fired on police vehicle and killed constable and injured two others in Mardan, said police. Police sources said that, during patrolling near Takhat Bhai on Malakand road in Mardan that unknown persons have opened fire on Police van. While during retaliation petrol wagon got uncontrolled and overturned. As a result, Head-Constable Imran Khan died on the spot, Constable Abdul Hameed and SHO Rasheed Iqbal of Sher Garh with his child suffered injuries. However, they have been shifted to hospital for medical treatment. Police has filed cases against the unknown criminals and started preliminary investigation.