Pakistan is critical of the US drone attacks
Two missiles, suspected to have been fired by a US drone, have killed one of the wives of a leading Pakistani militant, relatives have told the BBC.
The missiles struck the house of top Taliban commander Baitullah Mehsud's father-in-law, locals told the BBC.
They say that several other relatives of Mr Mehsud were injured in the attack in the South Waziristan tribal area.
The region is a haven for Taliban and al-Qaeda militants and has been repeatedly targeted by US drones.
Pakistan has been publicly critical of such attacks. The government says that they fuel support for the militants.
Most of the strikes have taken place in the tribal regions of North and South Waziristan.
The region is the stronghold of Mr Mehsud, who is Pakistan's top Taliban commander.
Four children were also injured in Wednesday morning's attack, local officials told the BBC.
The house is located in the Zangarha area, 15km (9.3 miles) north-east of Ladha town.
It was owned by Malik Ikramuddin, father-in-law of Baitullah Mehsud.
Mohammad Iqbal Mehsud, nephew of Malik Ikramuddin, told the BBC Urdu service's Dilawar Khan that more than 40 people were present in the house at the time of the attack.
They remained unharmed because they were in others rooms, he said.
He said Baitullah Mehsud was not in the house at that time.
Mr Ikramuddin was present but has remained unhurt, Mohammad Mehsud said.
Taliban and local residents have dug up the body of Baitullah Mehsud's wife from the debris, witnesses said.
The BBC's M Ilyas Khan in Islamabad says that she is his second wife - they married last year.
Residents say that the militants have set up check posts at points along roads near the area and have stopped traffic.
Our correspondent says that suspected US drones have carried out several attacks in areas controlled by Baitullah Mehsud in recent weeks, but this is the first strike in which his close relatives have been targeted.
The US military does not routinely confirm drone attacks but the armed forces and the Central Intelligence Agency operating in Afghanistan are believed to be the only forces capable of deploying drones in the region.
In March, US President Barack Obama said his government would consult Pakistan on drone attacks.