TEHRAN, Young Journalists Club (YJC) - Daesh claimed responsibility for the attack in Jalalabad, the capital of Nangarhar province. Among the four killed were two employees of the NGO, a security guard and an army soldier.
The assault started with a suicide bomber who detonated his explosives' vest at the provincial offices of Save the Children, said Attahullah Khogyani, spokesman for the provincial governor.
Security forces killed four other attackers, he said, adding that at least 26 people, including three members of the Afghan security forces, were wounded.
After eight hours the fighting subsided and Khogyani said he initially thought it was over but then the shooting picked up again.
Two hours later, it was finally over, he said.
Carolyn Miles, president of Save the Children, expressed "profound sadness" at the killing of the NGO's staff members in Jalalabad. She said four wounded staffers were receiving medical treatment.
"We are shocked and appalled at the violence, carried out against our staff in Afghanistan who are dedicated humanitarians, committed to improving the lives and wellbeing of millions of children across the country," Miles said.
Miles added that the organization had been working in Afghanistan since 1976, "providing life-saving health, education, nutrition and child protection programs that have helped millions of children." Save the Children also said it had temporarily suspended its work across Afghanistan.
In a statement on its Aamaq media arm, Daesh terrorist group said one of its suicide bombers with an explosive-laden vehicle and a subsequent raid targeted "British and Swedish foundations and Afghan government institutes."
Both the Taliban and Daesh are active in eastern Nangarhar province.
Khogyani said the security forces had managed to rescue 46 people, mostly employees of the Save the Children, as the attack unfolded.