The blast, occurred near the hospital, creates panic making people around the affected area to gone out of senses.
According to rescue sources, ambulances and law enforcement vehicles are rushing towards the blast spot.
Abbasi Shaheed Hospital, considered to be the third major public hospital, is situated in Nazimabad, next to Karachi Matric Board Office.
This is the third blast in the same area since morning.
At least six including security personnel got injured in one after another blasts near a security check of Rangers.
The post, situated near Board Office Chowrangi of Karachi, the port city of the country, was the victim of the unknown attackers.
Deputy Inspector General Karachi West Javed Alam says that unknown bikers threw crackers at a Rangers vehicle and fled just right away.
Within minutes, the bomb blasted at the same spot, he further said.
Injured persons are identified as Muneer, Ateeq, Nadim, Zamir and Muhamamd Nazir.
According to rescue services, injured persons were shifted to nearby Abbasi Shaheed Hospital.