A remote-controlled bomb targeting Shiite Muslims killed 52 people including women and children and wounded 200 in Pakistan's insurgency-hit southwest on Saturday, police and officials said.
The bomb exploded in a bazaar in Hazara town, an area dominated by Shiites on the outskirts of Quetta, capital of oil and gas rich Baluchistan province.
"The death toll is increasing. At least 52 people were killed in the bomb blast," Fayaz Ahmad, a senior police official told AFP.
Colonel Maqbool Ahmad, commandant of paramilitary group Frontier Corps Quetta, confirmed the new toll and warned it could rise.
Wazir Khan Nasir, a senior police officer in Quetta, said the bomb also left 200 people wounded.
"It was a sectarian attack, the Shiite community was the target," he said.
A spokesman for the banned Sunni Muslim extremist group Lashkar-e-Jhangvi claimed responsibility for the attack.
Provincial home secretary Akbar Hussain Durrani told AFP the dead and injured included women and children and said the blast collapsed a building at the bazaar, leaving some people trapped under rubble.
"We fear more casualties. We have announced an emergency in hospitals," he said.
Officials and witnesses said an angry mob initially surrounded the area following the blast and were not allowing police, rescue workers and reporters to reach the site.
"They were angry and started a protest, some of them pelted police with stones," Durrani said, adding that authorities and medical personnel were eventually able to gain access.
Sayed Qamar Haider Zaidi, a spokesman for Shiite groups in the area, condemned the Pakistani government for not providing protection to the community and announced three days of mourning and protest over the attack.
Baluchistan, which borders Iran and Afghanistan, has increasingly become a flashpoint for sectarian violence between Pakistan's majority Sunni Muslims and Shiites, who account for around a fifth of the country's 180 million people.
At least 92 people were killed and 121 wounded on January 10 when two suicide bombers blew themselves up at a crowded snooker club in an area of Quetta city dominated by the Shiite community.
It was Pakistan's worst sectarian bombing, also claimed by Lashkar-e-Jhangvi.
Pakistani Prime Minister Raja Pervez Ashraf late last month sacked the provincial government in Baluchistan after meeting Shiite Muslim protesters demanding protection.
The province is also rife with Islamist militants and a regional insurgency which began in 2004, with fighters demanding political autonomy and a greater share of profits from the region's natural resources.