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JALALABAD, Afghanistan — Four gunmen stormed an office of the Save the Children aid agency in Afghanistan Wednesday, killing at least five people and wounding 25, not including the assailants, officials said.

The attack began with a suicide car bomb outside the site in the city of Jalalabad, followed by gunmen entering the compound and fighting Afghan special forces, a spokesman for the provincial government said.

"There was a blast and the target was Save the Children," spokesman Attaullah Khogyani said. "Attackers entered the compound."

Some witnesses said the gunmen appeared to have been wearing police uniforms, a common tactic, but there was no immediate official confirmation.

Authorities said three Save the Children employees were killed, including one guard, as well as a member of the Afghan security forces and a shopkeeper.

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In addition to the suicide bomber who blew himself up, four other gunmen were shot by security forces. Witnesses said at least some of them were in police uniform, a commonly used tactic.

As security forces fought their way in, they recovered one body inside the compound.

"An explosion rocked the area and right after that children and people started running away," said Ghulam Nabi, who was nearby when the bomb exploded. "I saw a vehicle catch fire and then a gunfight started."

Islamic State claimed responsibility for the attack, according to the militant group's news agency Amaq, though it did not provide immediate evidence for the claim. The Taliban denied any involvement.

#Clarification

The ongoing attack in #Jalalabad has nothing to do with the Mujahidin of Islamic Emirate. — Zabihulla-M (@ZabihullaM4) January 24, 2018

Several other aid groups are located nearby, and security forces evacuated people from surrounding buildings while they exchanged fire with the militants.

"We are devastated at the news," a Save the Children spokesperson said in an emailed statement. "Our primary concern is for the safety and security of our staff."

The charity later announced that it had "temporarily" suspended all its programs across the country, but said it remained "committed to resuming our operations." Save the Children said in a statement that its aid reaches almost 1.4 million children throughout Afghanistan.

Backed by intensive U.S. airstrikes, Afghan forces have claimed growing success against the Taliban and other militant groups, including ISIS, but militant attacks on civilian targets have continued, causing heavy casualties.

The attack in Jalalabad came just days after Taliban militants struck the a hotel in Kabul, killing some 22 people, including at least 13 foreigners.