A senior police officer said militants hurled a powerful grenade at a passing police vehicle which exploded. The prisoner, Wahid Noor Khan, was being escorted to Central Jail Srinagar, police sources said.
Khan was arrested in connection with a militancy-related case of 2010 and was scheduled to appear before a Sessions court in Sopore.
"The accused was killed on the spot and five cops were seriously injured. They have been evacuated to hospital for treatment," the officer said.
Senior police officers along with reinforcements have reached the spot and the area has been cordoned off for searches.
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