ISLAMABAD: At least 20 persons were killed and more than 40 injured when a suicide bomber struck at a religious procession of Pakistan's minority Shia Muslims in Jacobabad town in southern Sind province on Friday.

Police said that Muharram procession of over 300 persons, including children and women, was passing through a six feet wide alley of Jacobabad's Lashari Mohalla when the attack occurred.

Malik Zafar Iqbal Awan, a senior police official, said that they have recovered body parts of the suicide bomber from the site. "It was a suicide attack and the head and some other body parts of the suicide bomber were found at the site," he said.

Security and rescue teams, however, rushed the dead and injured into Civil Hospital Jacobabad, where an emergency was declared. "The dead included four children. So far we have received 20 dead bodies and about dozens of others injured," a hospital representative told media.

This was the third attack in Pakistan in less than a week. At least 10 people were killed a day earlier when a suicide bomber blew himself up outside imambargah in restive southwestern Baluchistan province, while 11 people were killed earlier this week in bombing inside a passenger bus in Quetta, Balochistan's capital.

Footage aired by local TV stations showed the blood-splattered street and walls. Volunteers and distraught relatives in blood-soaked clothes were seen helping the wounded and taking them to nearby hospitals.

Prime Minister Nawaz Sharif, who is on a planned visit to the US, has expressed "deep grief and sorrow" over the attack, and ordered a special investigation into the incident.

Sectarian violence in Karachi, Peshawar, Quetta and the north-west is a manifestation of the bitter split between Sunnis and Shias. Over the past 20 years, Sunni and Shia extremists have attacked each other all over Pakistan.

Friday's blast was the second deadliest attack on minority Shia community congregation after 61 people were killed and at least another 60 were injured in a bomb explosion in an imambargah in upper Sindh district of Shikarpur on Jan 30, 2015.

The mourning of Muharram procession, which was disrupted by the bombing, is one of the central dates of the Shiite religious calendar. The gatherings and processions during Muharram mark the martyrdom of Hazrat Imam Hussain, grandson of Prophet Muhammad, in the Battle of Karbala, Iraq, in 680 AD.