According to details, unknown assailants lobbed a cracker at Imambargah Hussainiya Sajjadiya, in North Nazimabad and fled the scene.
As a consequence, three people standing outside were hurt, who were taken to hospital.
The cracker blast also damaged the entrance gate of the imambargah.
Meanwhile, a heavy contingent of police and Rangers reached the spot and cordoned off the site of blast.
