"An unknown person entered the reception of the FSB office for the Khabarovsk region office at 17:02 (0702 GMT) on April 21 without crossing the security check and began to shoot at the people in reception," the FSB said, AFP reported.
An FSB employee and a visitor were killed as a result of the shooting, it said. A second visitor was also injured.
The FSB said that the assailant had been killed, without providing any further details on the attack.