Saudi-led coalition jets on Sunday bombed a Houthi military position and army bases in the Yemeni capital Sanaa in what appeared to be further retaliation for the killing of dozens of coalition soldiers two days ago.
The air strikes targeted troops loyal to former President Ali Abdullah Saleh, an ally of the Houthis, and a Houthi base in what was the al-Imam University, a religious school in northern Sanaa, residents said.
A maternity and children's hospital said it had also sustained damage, with its patients trapped inside by the intensity of the bombardment.
Residents said explosions could be heard all night and buildings had been levelled but there were no immediate reports of casualties as most people in the area had been evacuated.
"The sounds of explosions had not stopped since 1:15 a.m. (2215 GMT)," one resident told Reuters.
The al-Sabeen hospital in Sanaa issued an appeal to international organisations to help it evacuate patients.
"The hospital had been badly damaged due to the bombardment of areas around it, which resulted in damage to various facilities," the Houthi-run state news agency quoted a hospital statement as saying.
The Saudi-led coalition says it does not target civilian facilities.
On Saturday, at least 24 members of two families were killed in Sanaa by air strikes targeting Houthi positions in the city, according to local medical sources. Hospital officials said on Sunday the death toll had risen to 27.
On Friday, the Iranian-allied Houthis had attacked a weapons storage facility in Marib, exiled President Abd-Rabbou Mansour Hadi's supporters had been massing troops and military hardware in preparation for an assault on Sanaa.
The attack killed 45 Emirati soldiers, five Bahrainis, 10 Saudis and four Yemenis.
It was the heaviest toll suffered by the Saudi-led alliance since air strikes began in March to try to restore Hadi to power after the Houthis began advancing on his main base in the southern port city of Aden.
United Arab Emirates forces were important in helping Hadi's supporters drive the Houthis and their allies out of Aden, a big win for the Arab coalition.