The dead reportedly include three members of the NATO-led ISAF force and four Afghan police officers.
An Interior Ministry spokesman, Najeeb Danish, confirmed the deaths of the six civilians and said several others were wounded in the attack on a joint NATO-Afghan foot patrol through the city of Khost.
The Khost governor's office said in a statement to RFE/RL's Radio Mashaal that the commander of a police rapid-reaction force based in Khost was among the dead.
ISAF spokesman Adam Wojack has confirmed that three NATO troops and their translator were killed in a bombing in the east, without giving an exact location or the nationalities of the dead.
Wojack said it was not immediately clear if the killed translator was an Afghan citizen or a foreigner.
A Taliban spokesman, Zabiullah Mujahid, claimed responsibility for the blast in text messages to media.