Amit Jethwa, the RTI activist, was shot from a close range by the assailants who fled on a motorcycle after the incident.
HM Kundaliya, a police inspector informed that Jethwa died on the spot after he was shot.
"His body was being sent for postmortem and search for the assailants was on," said Kundaliya.
Jethwa was very active in the conservation of wildlife, especially lions, in the Gir area.
Jethwa had recently filed a public interest litigation (PIL) in the high court against illegal mining in the Gir region of Junagadh district.
The Gir region is considered the last abode of Asiatic lions in the world.