Children were among at least 14 people killed in an air strike that toppled residential blocks in Yemen's capital Sanaa on Friday, witnesses and medics said.
The attack was the latest in a wave of deadly raids on residential areas of Yemen blamed on a Saudi-led Arab military coalition, drawing strong international condemnation.
The United Nations has accused the Arab coalition of killing 42 civilians in the week to Thursday, including many children.
Amnesty International's Middle East research director, Lynn Maalouf, said the coalition "rained down bombs on civilians while they slept".
She called in a statement for the UN to take action against Saudi Arabia over the list of civilian facilities struck in deadly air raids over the past two years.
"We are calling on the UN to look at the evidence – the schools and hospitals that lie in ruins, the hundreds of young lives lost to reckless air strikes," Maalouf said.
The International Committee of the Red Cross condemned the latest deadly raid as "outrageous".
"Eight of the victims were members of the same family, including five children between three and 10 years old," said the deputy head of the ICRC's delegation in Yemen, Carlos Morazzani, after visiting the site.
"Such loss of civilian life is outrageous and runs counter to the basic tenets of the law of armed conflict," he said. "From what we saw on the ground, there was no apparent military target."
Friday's air raid destroyed two buildings in the southern district of Faj Attan, leaving people buried under debris, said an AFP photographer on the scene.
His images showed severely damaged buildings, piles of smashed concrete blocks and splintered beams of wood.
Medics at the site said at least 14 people including six children and two women had died in the strike at 3:15 am (0015 GMT).
Al-Massira television channel, run by the Shiite Huthi rebels who control the capital, said those killed were all civilians, and blamed the Saudi-led coalition for the strike.
Mohammed Ahmad, who lived in one of the buildings, said he was among those who had taken nine bodies to a hospital.
"We extracted them one by one from under the rubble," he said.
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"When the rocket hit, one of the buildings was immediately destroyed which caused the building next door to collapse too. Some residents got out, but others were trapped."
Diggers worked at the site for hours after the raid as medics and residents searched for the missing. Survivors helped move the wounded to ambulances.
A man wearing a bloodied white gown walked among the torn and burnt pieces of clothing and bits of wooden furnishings.
- Series of strikes -
The coalition entered Yemen's war in 2015 in support of the government against the Iran-backed rebels, who seized Sanaa the previous year after forming a fragile alliance with troops loyal to former president Ali Abdullah Saleh.
The World Health Organization estimates that nearly 8,400 civilians have been killed and 47,800 wounded since the Saudi-led alliance intervened.
Friday's raid came two days after at least 35 people died in a series of strikes on Sanaa and a nearby hotel that rebels have also blamed on the coalition.
Coalition spokesman Colonel Turki al-Malki told AFP that those killed in Wednesday’s air strike were "armed militants", adding that the strike was aimed at "a high-value target".
He said he would "review the information" about Friday's strike.
Human rights groups have repeatedly criticised the coalition, which controls Yemen's airspace, over the civilian death toll from the bombing campaign on northern and southern Yemen.
The coalition has come under massive pressure from international organisations including the United Nations over the raids.
The UN has said the coalition was probably responsible for a July attack on the southwestern Taez province that killed 20 people, including children.
"In the week from August 17 to August 24, 58 civilians have been killed, including 42 by the Saudi-led coalition," UN human rights office spokeswoman Liz Throssell told reporters in Geneva on Friday.
Yemen also faces a deadly cholera outbreak that has claimed nearly 2,000 lives and affected more than half a million people since late April.
A combination of war, disease and a coalition blockade have pushed Yemen, long the poorest country in the Arab world, to the brink of famine.
The United States also regularly conducts deadly drone strikes on Yemen that Washington says target Al-Qaeda.