A deadly car bomb has hit a hospital in Afghanistan's eastern Logar province, with women, children and elderly among the casualties.
The provincial health director told the BBC that 27 people had died and 53 were hurt, adding the toll could have been higher as many people took away the bodies of relatives.
The facility was destroyed and people were buried under rubble.
Officials blamed the Azra district bomb on the Taliban, but they denied it.
A Taliban spokesman said they did not target civilians and that "someone with an agenda" was behind the blast.
The BBC's Bilal Sarwary in Kabul says the Taliban always distances itself from attacks with large numbers of civilian casualties.
There has been confusion over the death toll from Saturday's explosion as earlier the health ministry said 60 people had died, while local and Kabul officials gave differing totals.
An intelligence official said the hospital may not have been the intended target, because the suicide bomber detonated the device as police tried to stop his car.
A large number of people had been gathering at the clinic for weekly treatment, many of them women, children and elderly people, said provincial official Din Mohammad Darwaish.
Doctors and nurses were also said to be among the dead.
A man who lives near the hospital, Abdul Rahman, told AFP news agency he lost seven relatives in the blast.
"I was at home, then I heard a big explosion," he said. "When I rushed to the site, I saw many dead and injured people.
"Many of them were burning, on fire. There were body parts everywhere."
Soldiers were sent to the scene to rescue those trapped beneath the ruins.
A statement by the public health ministry, quoted by AFP, said: "This inhumane act is unprecedented in the history of the conflict in our country and targeted a place where wounds are healed and patients receive treatment."
A member of the Logar provincial council told the BBC: ''It is no less than a doomsday.
"The government and its intelligence agencies should have been able to prevent this. To the enemies of the people and Islam, I say, what do you get from a bloodbath like this?"
Our correspondent says local community members have recently joined the Afghan police, despite insurgent warnings not to do so.
He says there is almost no central government control over Azra, which is close to the Pakistan border, and insurgents and smugglers are well-established there.
There has never been an attack on a hospital in Afghanistan on this scale, he adds, although last month a suicide bomber attacked the main military hospital in Kabul, killing six people.
On Friday 10 people were killed and 24 injured by a bicycle bomb in northern Kunduz province.
Two days earlier, US President Barack Obama announced a partial troop pullout from Afghanistan.
He said 33,000 troops would leave this year, with the remaining 68,000 departing by 2013.
But there are concerns among the top US military that the withdrawal could endanger security gains.
A UN report earlier this month indicated a recent rise in civilian casualties.
It said May was the deadliest month for civilians in Afghanistan since records began in 2007, with 368 killed.
It added that 2,777 civilians died in 2010, making it the worst year, with three-quarters of the deaths blamed on insurgents.