Yemen's Houthi rebels claimed Monday to have shot down a Moroccan warplane participating in a Saudi-led air campaign against them, part of an escalation in fighting that could jeopardize plans for a five-day cease-fire intended to facilitate the delivery of aid to civilians.
Residents of the capital, Sana, said they came under some of the heaviest bombardments yet.
The focus of Monday's airstrikes appeared to be weapons storage sites on Noqom mountain, on the city's northeastern outskirts. The bombing caused explosions that sent shells flying into heavily populated neighborhoods.
At least 50 people were killed and more than 300 injured, according to Yemen's Saba news agency, which said the toll was expected to rise.
Morocco's military confirmed that one of its F-16 fighter jets has been missing since Sunday evening. It did not say what happened to the plane.
But a private Moroccan news site, Le360, reported that it was one of two jets that came under fire from rebel antiaircraft batteries while conducting a reconnaissance mission over the mountainous region on Yemen's northern border with Saudi Arabia. [Link in French]
If confirmed, it would be the first coalition aircraft shot down since the airstrikes began March 26.
Miserah television, a station loyal to the Houthis, reported that the jet was hit over Saada province, the birthplace of the rebel movement. It broadcast video of what it said were armed tribesmen posing with pieces of the wreckage, including one bearing the markings of the Royal Moroccan Air Force.
Photographs posted on Yemeni news sites and shared on social media were said to show body parts found at the site, but there was no immediate confirmation of the pilot's fate. A statement released by Morocco's military said the pilot of the second plane didn't see whether his comrade was able to eject.
The Saudi-led coalition has in recent days stepped up its airstrikes, pounding Houthi strongholds and military sites before the truce that is scheduled to take effect at 11 p.m. Tuesday.
In Sana, loud explosions continued into the night Monday. Terrified residents streamed from the affected areas, some of them in tears, as smoke billowed and flames lighted up the sky.
"The situation I am living in with my family is unspeakable," said Mohammed Ahmed Sheikh, who took shelter with his relatives in the basement of their home. "I don't know why they hate us that much."
The Health Ministry issued appeals over the radio and via cellphone text messages for blood donations and called on all medical personnel to report to city hospitals.
More airstrikes, shelling and clashes were reported in Saada, the focus of escalating violence that has displaced thousands, according to the United Nations.
A civilian was killed and four others were injured when shells were fired into Saudi Arabia from Yemen on Monday morning, the official Saudi Press Agency reported. The injured included three foreign nationals.
Saudi media later reported that the kingdom had sent a "strike force," including tanks and armored personnel carriers, to the border region. However, there were no signs that a ground offensive was imminent.
The fighting has caused massive casualties and damage to critical infrastructure in Yemen. Humanitarian officials have been calling for a pause in the hostilities to help ease the suffering of civilians, who have been racked by shortages of food, fuel and medical care.
Officials in Saudi Arabia, the region's Sunni Muslim power, say the campaign is meant to restore the internationally backed government of President Abdu Rabu Mansour Hadi, who was forced to flee to Riyadh, the Saudi capital, in March. They view the Houthis as proxies of Shiite Muslim-led Iran, which they accuse of attempting to put a client militia into power in their backyard.
The Houthis, who come from the Zaidi sect, a Shiite offshoot, say their alliance with Iran is political and not military. They are backed by members of the security forces still loyal to Ali Abdullah Saleh, the Yemeni president who was ousted in 2012.
Special correspondent Al-Alayaa reported from Sana and Times staff writer Zavis from Los Angeles. Special correspondent Amro Hassan in Berlin contributed to this report.