The 27 people injured are receiving medical treatment, Naqvi said.
He added that the attacker detonated the bomb close to a police car after waiting for up to 15 minutes.
Pakistani President Asif Ali Zardari said he “strongly condemned the suicide blast”.
Meanwhile, a lawyer who said he was parking his car outside the court at the time, described hearing a “loud bang”.
Rustam Malik told AFP news agency “it was complete chaos”.
“Lawyers and people were running inside the complex,” he added. “I saw two dead bodies lying on the gate and several cars were on fire.”
