(CNN) At least 14 people -- including one aid worker -- were killed when an airstrike hit a hospital in northern Yemen Monday, according to the humanitarian group Doctors Without Borders.
Twenty four people were injured in the attack on Abs hospital in Hajjah province, the group also known as Médecins Sans Frontier, or MSF, said on Twitter. The MSF staffer, Abdul Kareem al Hakeemi, died as a result of injuries caused by the blast, the group said.
The Saudi-led coalition carrying out airstrikes in Yemen said Tuesday it is aware of the hospital strike and will look into it. The Joint Incidents Assessment Team "has opened an independent investigation into these reports as a matter of urgency" and "will make its findings from this investigation public," the statement posted on the Saudi news agency SPA said.
MSF is still surveying the damage in the area and will launch its own internal investigation into the incident, the group said on Twitter.
At the time of Monday's attack, there were 23 patients in the surgery ward, 23 in the maternity ward, 13 newborns and 12 patients in the pediatric ward, MSF said. The hospital had a 14-bed emergency room, a maternity unit and a surgical unit and had seen an uptick in wounded patients in the last weeks, most hurt in clashes and in the bombing campaign, the group tweeted.
More than 4,600 patients have received medical help since MSF began supporting the hospital in July 2015 the group said on its website.
Beyond the immediate impact on civilians and children, the airstrikes are also having an impact on the health sector, according to UNICEF, which also supported the Abs Hospital.
"Health care is grinding to a halt and is on the verge of collapse," said Bismarck Swangin, UNICEF communication specialist in the Yemeni capital of Sanaa.
The country has become a proxy battleground between Iran and Saudi Arabia. The Arab coalition began launching airstrikes in support of the Sunni government against the Shiite Houthi minority rebels in March 2015. UN-led peace talks reached a dead end last week. An average of six children are killed or injured daily in the ongoing violence since March, Swangin said.
One Sanaa resident who spoke to CNN but did not want to be identified due to security concerns said that his house shook and his children were terrified as war planes flew overhead earlier in the morning. "The children are the ones who are most affected from this violence," he said. "We hear the screams of children in their schools when there is an airstrike."
The strike on the hospital comes on the heels of Saudi-led coalition planes bombing two schools in northern Yemen on Saturday, killing at least 14 children. The coalition insists the target of the airstrikes was a militia training camp.
It is not the first time a hospital supported by Doctors Without Borders has been hit in Yemen. In January, at least five people were killed and 10 others, including three Doctors Without Borders members, were injured when a hospital was hit in northern Yemen.
It's the fourth attack on an MSF-supported facility this year, the group said in a statement.
"After each attack MSF receives reassurances from the actors in the conflict with promises that this will not happen again," said Teresa Sancristóval, MSF emergency program manager. "We do not want words, courtesies, promises which go undelivered. What we need to see is proof of intent and a commitment that there will be no more airstrikes on medical facilities, staff and patients."
"This new incident shows that there are no effective measures in place to ensure that hospitals are not another casualty of war," Sancristóval continued. "MSF has shared the coordinates and information related to all its facilities in Yemen with all parties to the conflict, yet we have been hit four times. If the current military protocols are leading to 'mistakes' then those protocols have to be changed because they are destroying fully functioning medical facilities, staff, and patients."
Amnesty International called the hospital attack a "deplorable act" and potentially a war crime.
"Today's airstrike appears to be the latest in a string of unlawful attacks targeting hospitals highlighting an alarming pattern of disregard for civilian life," said Magdalena Mughrabi, deputy director of the Middle East and North Africa program. "Deliberately targeting medical facilities is a serious violation of international humanitarian law which would amount to a war crime. The circumstances of this attack must be thoroughly and independently investigated."
The U.S. State Department is "deeply concerned" about the reported hospital strike and is conferring with Saudi officials about civilian casualties, said spokeswoman Elizabeth Trudeau.
"We call on all parties to cease hostilities immediately," Trudeau said. "We would note that the Saudi committee that was designated to look into civilian casualties ... did share its findings with the UN. We believe that's a step forward in transparency, and as we've previously underscored we also call on them to publicly release those reports."