A suicide bomber has rammed an explosives-laden vehicle into a hospital, killing 11 people in north-west Pakistan, say police.
Another 16 people were injured by the blast at the Shia Muslim-run facility in Hangu district, Khyber Pakhtunkhwa province, according to police.
The explosion follows the start of the Islamic holy month of Muharram, which is especially important for Shias.
Meanwhile, a US drone plane killed four people in the neighbouring tribal belt.
Investigators suspect Friday's suicide bombing on the outskirts of Hangu was a sectarian attack. Sunni militant groups often target Shias during Muharram.
"A car rammed into the hospital while people were praying in a hall and we have reports of at least 11 killed," the news agency Reuters quoted Hangu police chief Abdul Rashid as saying.
A tractor and trailer carrying 250kg (550lb) of explosives were used for the attack, Hangu police spokesman Fazal Naeem told news agency AFP.
It was the fourth major suicide attack this week in Pakistan.
On Monday, two bombers killed more than 40 people as they attacked anti-Taliban militia talks in Mohmand, in the north-western tribal belt.
On Tuesday, a suicide attacker failed in an attempt to assassinate the chief minister of Pakistan's south-western province of Balochistan.
On Wednesday, a bomber blew himself up near a minibus in the town of Kohat, not far from Hangu, killing at least 16 people.
Friday's air strike on a vehicle and house in Khadar Khel, North Waziristan, killed four militants, according to Pakistani officials.
The report is difficult to verify because the region, which lies on the Afghan border, is one of the most dangerous in the world.
It would be the second drone strike in the region this week. The frequency of such attacks has increased under the administration of US President Barack Obama.