The republic's Interior Ministry said the attackers fired grenades and set off two explosions, killing the brother of Nazran prosecutor Girikhan Khazbiyev.
Four of the injured are said to be in critical condition.
Blasts and attacks on officials are common in Ingushetia, which borders restive Chechnya.
Today's attack came just two days after a prosecutor was killed in an explosion in the North Caucasus republic of Daghestan .
(compiled from agency reports)
The aftermath of a December 2002 Chechen resistance attack on the main government building in Grozny (epa)