TEHRAN, Young Journalists Club (YJC) - Three police officials, a security guard and a civilian were killed, Senior police official Muhammad Ashfaq said. Provincial health minister Yasmin Rashid confirmed the toll.
Police have said they are still investigating the nature of the blast, which occurred near the entrance gate for female visitors to the 11th-century Data Darbar shrine, one of the largest Sufi shrines in South Asia.
Husks of vehicles littered the pavement near the shrine as first responders rushed to the scene while armed security forces fanned out in the area.
It has been targeted previously, in a 2010 suicide attack which killed more than 40 people.
Since then the area has been increasingly hemmed in by heavy security, with visitors forced to pass through several layers of screening before they can enter the complex.
A Pakistani Taliban faction Hizbul Ahrar claimed responsibility for the blast, Reuters said.