The International Committee of the Red Cross (ICRC) office in the eastern Afghan city of Jalalabad came under attack on Wednesday, a spokesman for the Geneva-based organisation said.
A large explosion was heard near the ICRC office in Nangarhar province and heavy gunfire was ongoing, a Reuters witness said. Black smoke billowed out of the building after the blast at 5:30 p.m. (1300 GMT).
No further details were immediately available.
ICRC's $90 million-a-year operations in Afghanistan are the group's biggest in the world. Some 1,800 ICRC staff work on projects ranging from providing orthopedic limbs to the war wounded to visiting militants in Afghan jails.