A bomb attack in Pakistan's largest city Karachi on Sunday killed at least 23 people, including women and children, and wounded 50 others, police said.
The blast hit close to an area dominated by minority Shiite Muslims, senior police official Ghulam Shabir Sheikh told AFP, though he said that the target of the attack was not immediately clear.
"At least 23 people have been killed and more than 50 injured. The bomb also badly damaged two residential buildings. Women and children were among the dead and injured," Fayaz Lughari, police chief of Sindh province, of which Karachi is the capital, told AFP.
He said the initial blast was followed by a second, but it was unclear whether or not this was also a bomb.
Ethnic, sectarian and politically-linked violence in Pakistan's financial capital killed at least 2,284 people in 2012 in the deadliest such violence for two decades, according to the independent Human Rights Commission of Pakistan.
Salman Ahmed, a spokesman for Edhi foundation rescue service, confirmed the blast and said the wounded had been taken to three different hospitals around the city.
On Monday a bomb blast at a Sufi shrine in southern Shikarpur district, some 400 kilometres (250 miles) northeast of Karachi, killed two people and wounded 10 others as devotees gathered to pay homage to a saint buried there.
Last month the Supreme Court ordered the authorities to come up with a strategy to protect Shiites after a wave of bloody attacks in the southwest.
Two major bombings in the space of five weeks targeting Shiite Hazaras in Quetta, capital of the southwestern province of Baluchistan, killed nearly 200 people.
Both attacks, the latest on February 16, were claimed by the banned extremist Sunni group Lashkar-e-Jhangvi, and have highlighted the government's inability to stem sectarian violence.
Shiites, who make up around 20 percent of the mostly Sunni Muslim population of 180 million, are facing a record numbers of attacks.
The Pakistani Taliban have also increased their campaign of violence in recent months, leading to fears that violence could mar a general election scheduled to take place by mid-May.
Last month the group proposed talks with Islamabad but the government insists the militants must declare a ceasefire before coming to the negotiating table -- a condition militants have rejected.