Terrorists on Friday targeted a bus carrying a group of people to a Shia religious procession as well as a hospital in Karachi, killing at least 22 people and injuring over 50, in the latest in a wave of attacks across the country.
The explosion targeting the bus occurred on Shahrah-e-Quaideen, a key thoroughfare in the city, at 3.05 pm local time.
Provincial Health Minister Sagheer Ahmed said 12 people were killed and 50 injured in the attack.
TV news channels quoted witnesses as saying that a motorcycle-borne suicide bomber rammed the bus.
However, Karachi police chief Waseem Ahmed said initial investigations had indicated that an explosive device planted in the motorcycle was triggered by a remote control as the bus was passing by.
The second blast occurred at approximately 5 pm local time outside the emergency ward of the Jinnah Post Graduate Medical Centre Hospital.
Geo news channel quoted officials and witnesses as saying that ten people were killed and several others injured in the second blast. Several ambulances were also damaged in the attack.
Over 200 people, most of them relatives of the injured in the first blast and rescue workers, were present outside the hospital at the time of the explosion, the cause of which is yet to be ascertained.
Karachi police chief Ahmed appealed for calm and urged Shia mourners to go ahead with the main procession marking the 'Chelum' or 40th day of the martyrdom of Hazrat Imam Hussain.
He said the blast targeting the bus, which was carrying mourners including women and children, had occurred at a considerable distance from the venue of the main procession and might have been aimed at diverting the attention of the security forces.
Security personnel cordoned off the area and gathered the pieces of the motorcycle believed to have been used in the attack.
This is the second time that a Muharram procession had been attacked by militants in the recent weeks. On December 28, a bomb explosion in the main Muharram congregation killed 45 people and led to widespread rioting.
Today's blast took place despite heavy security arrangements in the city, for the Muharram Chehlum processions, in the wake of recent sectarian killings that claimed 48 lives.
The government has given the paramilitary rangers sweeping powers under the anti-terror laws to control the law and order situation in the city.
Pakistan has witnessed a string of deadly attacks since October last year when the military launched an operation in the Taliban stronghold of South Waziristan. Hundreds of people have been killed in these attacks.