An air raid by an Arab coalition killed 60 people in Yemen, including inmates of a prison near the city of Hodeidah, medical sources said.
The prison held 84 inmates when it was struck three times late on Saturday, Hashem al-Azizi, deputy governor of the province of Hodeidah, told Reuters.
The Saudi-led alliance that conducted the raid said it struck a "central security building" used as a military command center by the Houthi rebels it is fighting.
Local officials said the prison lies within a security complex but that only prison guards were present during the air strike.
"This building is used by Houthi militia and the forces of the deposed president as a command and control center for their military operations," a statement by the coalition said, referring to former president Ali Abdullah Saleh, a Houthi ally.
"The coalition forces' leadership stresses that targeting protocols and procedures were followed fully," the statement said.
The Saudi-led coalition has been fighting Yemen's Houthi movement since March 2015.
It wants to restore the internationally recognized president, Abd-Rabbu Mansour Hadi, who was driven into exile by the Iran-allied Houthis in late 2014.
A Reuters witness at the security complex said the building was destroyed and medics pulled about 17 bodies away, many of them missing limbs.
Others remained trapped under the rubble.
One of the strikes directly targeted the building, the witness said, bringing it down over the heads of the prisoners.
Two others hit the gate of the complex and nearby administration buildings.
The air attack was one of the deadliest among thousands of bombings.
The attacks have largely failed to dislodge the Houthis from the capital, Sanaa, but have repeatedly hit schools, markets, hospitals and homes, killing many civilians.
HADI REJECTS PEACE PLAN
Rights groups have said the raids may amount to war crimes, but an investigative body set up by the coalition largely defended its methods in an August report, which concluded that Houthi rebels regularly deploy to civilian sites.
The Houthis deny this, and a top official in the movement criticized the United Nations and the United States, the Saudis' key ally and arms supplier, for not doing enough to hold the kingdom accountable for its air strikes.
"We condemn the position of the international community and the U.N. for providing cover for the crimes of Saudi Arabia against Yemenis, and they are subject to the wishes of America," Saleh al-Samad said in a statement late on Saturday.
The bombing may signal a renewed outbreak of violence a day after Hadi rejected a new U.N. peace proposal, saying the deal would only be a path to more war and destruction.
Speaking after a meeting with U.N. envoy Ismail Ould Cheikh Ahmed in Riyadh, Hadi said the agreement would "reward the rebels and penalize the Yemeni people and legitimacy", according to the government-controlled Saba news agency.
According to a copy of the proposal seen by Reuters, the plan would sideline Hadi and set up a government of less divisive figures.
Hadi's opponents accuse him of commanding only a small support base in Yemen and of being unable to bring its warring factions together, since he invited the Saudi-led coalition to intervene in the civil war.