At least three policemen were injured when a suicide bomber blew himself up outside the Khanpur Imambargah on Tuesday, police said. 

Two suicide bomber were trying to enter the imambargah where people had gathered for Eid prayers, police said.

One of the suicide bombers was arrested in an injured condition.

The injured were shifted to the hospital.

Additional contingents of police have been deployed at the blast site.

IG Sindh AD Khwaja said the injured policemen were in critical condition and have been shifted to Sukkur. "If the need arise we will bring them to Karachi for treatment."

Chief Minister Murad Ali Shah visited the blast site.