Pakistani officials say since Monday, more than 70 people have died in bombings across the country. In the latest attack, police say a bomb blast near an intelligence office in the central city of Multan killed at least 12 people and severely damaged several buildings.
Police officials in Multan say at least two armed militants drove a vehicle loaded with about 1,000 kilograms of explosives into a complex housing an office of the country's ISI spy agency.
Officials say the militants blew themselves up after security forces stopped them from driving closer to the ISI office. The force of the explosion ripped the facades off several houses in the area.
Retired Brigadier-General Mahmood Shah is the former security chief for Pakistan's tribal regions. He tells VOA he believes the attack is the work of Punjabi militants, who used to train with the Pakistani Taliban in their South Waziristan stronghold.
"All these elements who were training there, who were stationed there, are out of the place and could be acting independently," he said.
He says security forces should become stricter in how they check individuals and search vehicles for explosives.
Late Monday, twin explosions struck a busy market in the eastern city of Lahore, killing nearly 50 people, mostly women and children.
Earlier in the northwestern city of Peshawar, a suicide bomber exploded outside a courthouse, killing 10 people.
No one has claimed responsibility for the attacks, but officials are blaming Taliban militants.
Since the Pakistani military launched operations against them near the Afghan border in mid-October, most of the militant attacks have targeted security forces, including the country's separate army and naval headquarters.
Militant attacks across Pakistan have killed more than 500 people in the past two months.