An airstrike on the port city of Hodeida has wiped out internet services across Yemen.
Dozens of people have been killed and injured after Saudi-led airstrikes on cities in northwestern Yemen, according to officials and NGOs.
One attack on Friday hit a detention centre in Saada, a city controlled by Houthi rebels since 2014.
More than 100 detainees were killed or wounded, said Basheer Omar, an International Committee of the Red Cross spokesperson in Yemen.
“The toll is likely to increase, unfortunately,” Omar said, adding that the Red Cross had moved some of the wounded to facilities elsewhere.
An earlier airstrike on the port city of Hodeida had also struck a telecommunications centre, wiping out internet connectivity for many in the country.
The intense campaign comes after the Houthis claimed a drone and missile attack on an Abu Dhabi industrial area on Monday, killing three people and wounding six.
Save the Children say that the series of airstrikes on Yemen have killed at least three children and more than 60 adults, while at least 100 others were injured.
Aid workers and paramedics continue to clear the rubble with more casualties expected to be discovered in both cities, the NGO said in a statement.
Doctors Without Borders said a hospital in Saada had received 138 wounded people, while another 70 had been killed.
“There are many bodies still at the scene of the airstrike, many missing people,” Ahmed Mahat, the organisation’s head of mission in Yemen, said in a statement.
“It is impossible to know how many people have been killed. It seems to have been a horrific act of violence.”
The internet monitoring observatory NetBlocks said that the earlier airstrike on Hodeida left Yemen facing a “nation-scale collapse of internet connectivity”.
NetBlocks say the internet disruption began around 01:00 local time and has remained for several hours.
The Norwegian Refugee Council decried the strike on Hodeida as “a blatant attack on civilian infrastructure that will also impact our aid delivery.”
The Saudi-led coalition has acknowledged carrying out “accurate airstrikes to destroy the capabilities of the militia” around Hodeida’s port but did not immediately acknowledge the strike in Saada.
Saudi authorities have called Hodeida a hub for piracy and Iranian arms smuggling to back the Houthis.
Iran has denied arming the rebels, but UN experts, independent analysts, and Western nations point to evidence showing Tehran’s link to the weapons.
The Saudi-led coalition entered Yemen’s civil war in 2015 to try and restore to power the country’s internationally recognised government, ousted by the Houthis a year before.
The war has turned into the world’s worst humanitarian crisis, with international criticism of Saudi airstrikes that have killed hundreds of civilians and targeted the country’s infrastructure.
The Houthis meanwhile have used child soldiers and indiscriminately laid landmines across the impoverished country. An estimated 110,000 people have been killed so far in the conflict.
On Thursday, UN Secretary-General Antonio Guterres said he was alarmed at the ongoing airstrikes in the capital Sanaa, Hodeida, and other locations in Yemen, as well as separate shelling attacks.
"Yemen continues to be one of the most dangerous places to be a child today, and children are bearing the brunt of this crisis," said Save the Children’s Country Director in Yemen, Gillian Moyes.
"They are being killed and maimed, watching as their schools and hospitals are being destroyed, and denied access to basic life-saving services."
“The initial casualties report from Saada is horrifying," she added.
"Migrants seeking better lives for themselves and their families, Yemeni civilians injured by the dozens, is a picture we never hoped to wake up to in Yemen”.