Planes from a Saudi-led coalition have kept up air strikes targeting Yemen's Shiite rebels and their allies around the capital Sanaa, hours ahead of a humanitarian ceasefire.
The strikes stopped shortly before the newly appointed UN envoy to Yemen, Ismail Ould Cheikh Ahmed of Mauritania, flew into Sanaa on his official first visit to the country.
He told reporters he planned to meet various parties, including the rebels known as Houthis, and ensure that the ceasefire holds.
According to security officials, air strikes overnight, at dawn and during the morning targeted weapons depots and other military facilities north and south of Sanaa, a sprawling city of four million people.
The military air base that is part of the capital's international airport was also targeted.
In all, Sanaa endured 10 strikes from dawn until about noon, the officials said.
The ceasefire, scheduled to begin tonight, is meant to help ease the suffering of civilians in Yemen, the Arab world's poorest country.
The conflict has killed more than 1,400 people - many of them civilians - since March 19, according to the UN, and the country of 25 million has endured shortages of food, water, medicine and electricity as a result of a Saudi-led naval, air and land blockade.
Today's air strikes came a day after the coalition pounded a mountainside on the north-eastern edge of Sanaa, hitting arms and ammunition depots. The bombardment shook the entire city, collapsing some homes and shattering windows. They also caused shells to explode in the arms depots, and the munitions hit residential areas and started fires.
The health ministry said preliminary figures showed that yesterday's airstrikes in Sanaa killed 10 and wounded 162, mostly civilians.
The officials said the strikes were among the strongest in Sanaa since the air campaign began on March 26 against the Houthi rebels and their allies in the army and security forces loyal to former president Ali Abdullah Saleh.
Saudi Arabia and its coalition of Sunni Arab countries began the air strikes to break the advance of the Houthis and Saleh's forces, who overran Sanaa and much of northern Yemen late last year and have been on the offensive in the south.
The Saudis and their allies are seeking the restoration of president Abed Rabbo Mansour Hadi, who fled the country in March in the face of the Houthi advance.
Human Rights Watch said today that the Houthis have intensified the recruitment, training, and deployment of children in the conflict, in violation of international law. Since the rebels seized Sanaa in September, it said, the Houthis have increasingly used children as scouts, guards, runners and fighters, with some children being wounded or killed.
"The Houthis and other armed groups using child soldiers in Yemen should immediately stop recruiting children, including 'volunteers', and release all children in their ranks," it said.
The security officials said the Houthis were recruiting boys as young as 15 in Sanaa to fight in Saada, the rebel stronghold north of the capital, against Sunni tribesmen trying to enter the province that sits along the border with Saudi Arabia.
Islamic militant websites, meanwhile, said that four leading members of Yemen's al Qaida branch were killed yesterday in a suspected US drone strike in a southern port city.
The four died in Mukalla on the Arabian Sea, where rockets believed to have been fired by US drones hit al Qaida militants based in the city's presidential residence, according to security officials.
The militant Aamaq outlet, affiliated with the more extreme Islamic State group, said the four included Maamoun Hatem, reportedly an IS sympathiser. The three other militants were identified as Abu Anwar al-Kutheiri, Mohammed Saleh al-Ghorabi and Mabkhout Waqash al-Sayeri.
The compound in Mukalla was recently captured by al Qaida's branch in Yemen, viewed by Washington as the terror group's most dangerous affiliate.
Fierce fighting also raged in Taiz between the rebels and forces loyal to Hadi, officials said.
The rebels and their allies also shelled residential areas in the strategic city south-west of Sanaa, with one shell hitting a bus, killing nine people and wounding 40, officials said.
An air strike targeted the city's al-Qahira castle, from which the shelling came, they said.
Anticipating the truce, the UN refugee agency, UNHCR, said it plans to airlift 330 tons of sleeping mats, blankets, kitchen sets and plastic sheeting from stockpiles in Dubai.
The airlift, it said, is part of what it called a "larger aid mobilisation under way for a quarter of a million people". The agency will attempt to distribute aid already stored in Yemen and assess the needs for areas that have been difficult to reach.
Separately, the UN World Food Programme said it was ready to provide emergency food rations to more than 750,000 people.
A WFP-chartered vessel, meanwhile, arrived in the Red Sea port of Hodeida on Saturday, carrying 66,000 gallons of fuel and supplies for other humanitarian agencies. A second vessel is ready to dock with an additional 31,700 gallons of fuel.