An explosion at a US airfield in east Afghanistan killed four people and wounded another 14. Saturday's attack occurred at the Bagram Airfield, a main US military base in Afghanistan.

A US military official says the bombing was caused by an "explosive device".  Defense Secretary Ash Carter said two members of the armed services and two contractors died.

The Taliban says their suicide bomber carried out the attack.  A local government official said initial probes found the bomber was disguised as a daily worker. He passed the first checkpoint and detonated his explosive jacket. Military officials say the incident is being investigated.