Afghan officials say at least 11 people have been wounded in an attack on the office of international aid agency Save the Children in Jalalabad.
A suicide attacker detonated a car bomb outside the organization's provincial office in the eastern city on January 24, said Attaullah Khogyani, spokesman for the governor of Nangarhar Province.
Gunmen then entered the building, and fighting between the attackers and security forces was ongoing, Khogyani said.
"At around 9:10 a.m. a suicide attacker detonated a car bomb at the entrance of Save the Children's compound," he said. "A group of armed men then entered the compound. So far 11 wounded people have been brought to hospitals."
There was no immediate claim of responsibility for the attack, which comes after Taliban gunmen stormed a luxury hotel in Kabul on January 20, killing at least 30 people including 14 foreigners.
The Western-backed government in Kabul has been struggling to fend off the Taliban and other militant groups since the withdrawal of most NATO troops in 2014.
Inamullah Miakhial, spokesman for the Nangahar regional hospital, confirmed the casualty toll.
Mohammad Amin, who was inside the compound when the attackers stormed in, told AFP news agency that he heard "a big blast."
"We ran for cover and I saw a gunman hitting the main gate with a [rocket propelled grenade] to enter the compound. I jumped out of the window," he said.
Another witness said, "I am hearing gunfire from inside Save the Children compound."
Television news channels showed a plume of black smoke rising above the compound and what appears to be at least one vehicle burning outside the office.
An employee of Save the Children, who wanted to remain anonymous, was quoted as saying that around 100 people work at the building.
There are several other aid groups and government offices in the area.
Jalalabad is the capital of Nangarhar Province, which borders Pakistan.
The province is a stronghold for the extremist group Islamic State and also has a significant Taliban presence.
Save the Children is one of the largest relief organizations in Afghanistan, where it carries out educational, health-care, and protection work for children.
Foreign aid groups working in Afghanistan have been targeted in the past.
The International Committee of the Red Cross announced in October that it would "drastically" reduce its presence in the country after seven employees were killed in attacks last year.