Gunmen stormed into an office of the Save the Children aid agency in Afghanistans restive east on Wednesday, witnesses and officials said, killing at least two people and wounding 12 others. The attack began with a suicide car bomb outside the office at around 9.00 a.m., followed by gunmen using a rocket-propelled grenade to storm the complex, a spokesman for the government in the eastern province said. Schoolchildren and residents fled the area as Afghan Special Forces arrived to engage the attackers. “There was a blast and the target was Save the Children,” said Nangarhar governor spokesman Attaullah Khogyani. Security forces swarmed the compound after the attackers launched the morning raid and brought the assault to an end after more than three hours, AFP quoted Khogyani as saying. "The fighting has ended. The security forces are clearing the building now," Khogyani said. "Our initial information shows the attackers had military uniforms on." Mohammad Amin, who was inside the compound when the attackers launched the raid, told AFP from his hospital bed that he heard "a big blast". "We ran for cover and I saw a gunman hitting the main gate with an RPG (rocket-propelled grenade) to enter the compound. I jumped out of the window," Amin said. Afghan TV news channels showed a thick plume of black smoke rising above the compound and what appeared to be at least one vehicle on fire outside the office. ISIS claimed responsibility for the attack after the Taliban had issued a statement denying involvement. "We are devastated at the news that our Save the Children office in Jalalabad city, Afghanistan came under attack this morning," a Save the Children spokesperson said in a statement, withholding further details while the attack was ongoing. The UNs mission in Afghanistan tweeted that it was looking into reports of the attack. "Attacks directed at civilians or aid organizations are clear violations of international humanitarian law and may amount to war crimes," it said. The assault on Save the Children, which has operated in Afghanistan since 1976, is the latest violence to strike a foreign aid group in the country. The International Committee of the Red Cross announced in October it would "drastically" reduce its presence in the country after seven employees were killed in attacks last year. The decision by the charity, which has been working in Afghanistan for over three decades, underlined the growing dangers for aid workers, who have increasingly become casualties of a surge in militant violence in recent years. Nangarhar, a restive province bordering Pakistan, is a stronghold for the ISIS group and also has a significant Taliban presence. The province has become a stronghold for ISIS, which has grown to become one of Afghanistan’s most dangerous militant groups since it appeared around the beginning of 2015. Backed by intensive US air strikes, Afghan forces have claimed growing success against the Taliban and other militant groups, including Islamic State, but militant attacks on civilian targets have continued, causing heavy casualties. The attack in Jalalabad came just days after Taliban militants attacked the Hotel Intercontinental in the capital, Kabul, killing at least 20 people, including 13 foreigners. The attack underlined how difficult operating in Afghanistan has become for humanitarian aid organizations which have faced heavy pressure from armed groups and kidnappers.