Iran-backed Houthi rebels attacked a cancer treatment centre in Yemen’s south-west Taez province on Saturday, wounding staff members.
Two other health centres in Taez were hit, said Doctors without Borders (MSF), who condemned the attacks on “civilian infrastructure, including hospitals”.
“Patients were relocated to lower and more blast-protected areas of the facilities,” said Craig Kenzie, the MSF's Taez co-ordinator.
Mr Kenzie said some patients were moved to a Swedish medical facility, also supported by MSF, “not knowing that it would be hit in the next hours”.
Ali Sarhan, manager of the Human Rights Office in Taez, told The National that the rebels used mortars and heavy weapons.
“They targeted the cancer facility with two mortar shells followed by a barrage of Shilka-23 bullets, which were fired over residential neighbourhoods in central Taez,” Mr Sarhan said.
The Shilka is a Soviet-era anti-aircraft weapon capable of firing as many as 4,000 large-calibre bullets a minute.
MSF also reported that shelling had hit nearby Al Jomhouri hospital, injuring two civilians, in attacks that lasted all morning.
Dozens of patients, including children, who were receiving treatment at the cancer centre were moved to safety, Mr Sarhan said.
“The clinic suffered extensive damage and had only just re-opened its doors in February following a similar Houthi attack in 2015,” he said.
Taez is Yemen’s third-largest city and was once known as the country’s capital of culture.
It has suffered extensively in the nearly six-year conflict sparked by the Houthi takeover of the capital.
Isolated by a decrepit road network and rugged, mountainous terrain, the city's vital services have been harmed by the destruction of transport infrastructure.
The cancer clinic is run by a non-profit organisation funded through donations and provides patients with therapeutic and social support, said its head, Dr Mukhtar Al Mikhlafi.
“Targeting the hospital in such a manner is a disaster and a big violation for the rights of 8,500 cancer patients who regularly visit the facility,” Dr Al Mikhlafi said.
“We call on all the warring parties to shoulder their responsibilities to protect the centre and call upon the UN, its special envoy to Yemen, the World Health Organisation and international human rights organisations to protect the cancer patients.
The attack on the cancer clinic in Taez came days after similar Houthi assaults on health centres in Hodeidah, amid a recent escalation despite a UN-brokered ceasefire.
On October 11, two civilians were killed and dozens were injured when Houthi rebels attacked healthcare centre in Al Duraihimi, eastern Hodeidah.
Previously, another health centre in Al Hawak district was struck by the Houthis, only days after maintenance work was completed.
The Yemeni war has caused what the UN describes as the world’s worst humanitarian crisis and hit the health sector hard.
There have been outbreaks of infectious diseases, including cholera, and widespread malnutrition and hunger, while treatment for long-term illnesses such as cancer are hard to find.