At least five persons were killed and many others injured after two unidentified miscreants targeted mourners gathered in Nazimabad area in connection with month of Muharram on Saturday.
The death toll is feared to go up as at least two people are critically injured.
The gun attack took place in a residential area near a police station in Nazimabad No 4 area of the city. A Rangers station is located merely half a kilometer from the attack site.
According to police, two gunmen riding a bike entered a street in Nazimabad and attacked a majlis (Shia religious gathering) which was under way in a tent.
Rescue officials confirmed that five people perished in the firing incident. Those killed or injured in the attack were shifted to Abbasi Shaheed Hospital.
Police and Rangers reached the scene, cordoned off the area and launched a probe.
Initial probe suggests that there were four attackers. Two assailants targeted the male participants of the majlis while their accomplices gave them a cover.
According to an eyewitness, two gunmen wearing helmets opened fire on the male section of the majlis at 5:45 and escaped.
Taking notice of the incident, Sindh Chief Minister Murad Ali Shah made a telephone call to Sindh police chief and asked him to bring the perpetrators of the terrorist attack to justice.
On the other hand, IG police Mushtaq Mehr asked for a report about the attack.
Police say many empty shells of 9mm firearm were recovered from the scene of attack.
According to the police, the participants had not informed the department of a gathering in the area which was why there were no security arrangements.
Prime Minister Muhammad Nawaz Sharif has strongly condemned attack on innocent people in Nazimabad Karachi and directed the concerned authorities at the Federal and provincial levels to hunt down the culprits on immediate basis.
Expressing deep grief and sorrow over the loss of innocent lives during the attack, the Prime Minister prayed for eternal peace of the departed souls and grant of courage to the bereaved families to bear this irreparable loss.
The Prime Minister prayed for swift recovery of those injured during the attack.
This heinous attack will not go unpunished. We will not allow terrorists to disturb peace in Karachi. The perpetrators do not deserve mercy and they will be brought to task sooner, the Prime Minister stated.
In a separate statement, Interior Minister Chaudhry Nisar Ali condemned the terrorist attack.