Suicide bombers have attacked the residence of a military official in the Pakistani city of Quetta, killing at least 20 people.
The first attacker detonated a car bomb, and a second militant blew himself up in the house of the city's Frontier Corps chief.
Some of the dead were members of the corps - a paramilitary force battling militants on the Afghan border.
The Taliban have said they carried out the attack.
Their spokesman Ehsanulla Ehsan said that the target was Frontier Corps chief Farrukh Shahzad, to avenge his role in the killing of five Chechens in May by Pakistani forces in Quetta's Khrotabad area.
The Frontier Corps also took part in an operation to catch an al-Qaeda militant earlier this week, according to the army.
Militants linked to al-Qaeda and the Taliban, as well as ethnic Baloch militants, are active in the province.Thaw in relations
Police official Hamid Shakil told AFP news agency that at least four members of the Frontier Corps had been killed in Wednesday's bombing.
Mr Shahzad's wife and two of his children were among the dead.
"It was a twin suicide attack. The house was badly damaged. The deputy inspector general himself is injured," Mr Shakil said.
At least 44 people were injured in the explosions, he said. It is expected that the number of dead will rise.
Correspondents say that the residence of the deputy inspector general is close to government buildings and official residencies in Quetta, the main city in Balochistan.
On Monday the army announced that the Frontier Corps had arrested Younis al-Mauritani, blamed for planning and executing international operations for al-Qaeda.
He was detained in the suburbs of Quetta along with two other high-ranking al-Qaeda suspects after US and Pakistani spy agencies joined forces, according to the Pakistan army.
Correspondents say that the arrests were another blow to the global terror network, four months after Osama Bin Laden was killed in Pakistan by covert US forces.
While his death led to a souring of ties between Islamabad and Washington there may now be a thaw in relations, correspondents say.
The army has hailed co-operation between the CIA and Pakistan's Inter-Services Intelligence agency in the arrests, news of which came just days before the 10th anniversary of the September 11 attacks.
The US also praised the operation, with a White House spokesman describing it as an example of partnership between the two countries "which has taken many terrorists off the battlefield over the past decade".