KABUL, Afghanistan -- A group of gunmen stormed a non-governmental children's organization in Afghanistan's eastern Nangarhar province on Wednesday, killing at least four people, according to provincial officials.

The media office for Nangarhar province told CBS News four people were killed, including two members of the security staff at the Save the Children office. At least 25 others were left wounded in the attack, including four more of the charity's guards.

Attahullah Khogyani, spokesman for the provincial governor, said the attack on the compound in the city of Jalalabad was over after a protracted firefight.

I’m horrified by the cruelty of today’s attack on @SavetheChildren in #Jalalabad. Targeting children and organizations that support them is inhumane, and I hope those behind this attack are quickly brought to justice. #Nangarhar #Afghanistan — John R. Bass (@USAmbKabul) January 24, 2018

He said at least 14 people had been brought to local hospitals.

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The attack started with a suicide bomber and was followed by gunfire, said Khogyani.

Zabihullah Mujahid, a Taliban spokesman, said the Taliban was not involved in the attack; both Taliban insurgents as well as Islamic State of Iraq and Syria (ISIS) fighters are active in eastern Nangarhar province.

ISIS' Afghan branch, known as ISIS Khorasan, issued a statement several hours after the attack claiming responsibility for, "a martyrdom-seeking operation using an explosive-laden vehicle and three commandos," but it also claimed multiple Western targets were hit. ISIS often embellishes its own battle field operations in statements released via its online propaganda outlets.

Save the Children said in a statement that it had closed all offices and temporarily suspended operations across Afghanistan, but that it was "committed to resuming" its work as soon as possible.

U.S. Ambassador to Afghanistan John Bass expressed his condolences to the victims of the attack in a tweet, adding, "I hope those behind this attack are quickly brought to justice."

The attack follows a deadly weekend siege of the Intercontinental Hotel in the capital Kabul in which 22 people were killed, including 14 foreigners. Multiple U.S. citizens were killed and injured in the Taliban's 13-hour siege of the hotel, the State Department said Tuesday. No exact figures were immediately available for either the U.S. fatalities or injuries.

Eleven of the 14 foreigners had been previously identified as working for the private Afghan airline KamAir. During a ceremony at Kabul's airport Wednesday the bodies of seven Ukrainian citizens were handed over to officials for transfer to Ukraine.

An Afghan policeman keeps watch at the Intercontinental Hotel in Kabul, Jan. 23, 2018, three days after an attack by Taliban militants who killed at least 22 people at the luxury hotel often used by foreign travelers and dignitaries. Getty

Mirwais Samadi, head of the consulate department of the Afghanistan Foreign Ministry, said the attack was launched by "terrorists" and their supporters.

"Some of our countrymen were martyred and some foreign nationals also were killed," he said. "We express our condolences and thoughts to the victims and families."

In eastern Ghazni province, meanwhile, four Afghan police were killed after their checkpoint came under an attack by insurgents, said Arif Noori, spokesman for the provincial governor.

Six insurgents were killed and three were wounded in the battle, which took place early morning Wednesday in Dayak district, said Noori.