MEXICO CITY - Two gunmen walked into a radio station and killed a local activist while he was giving his weekly radio program, prosecutors in the northern Mexico state of Sinaloa said. It was the first on-air killing in recent memory in Mexico.

The victim, Atilano Roman Tirado, was the leader of a group of about 800 farm families whose lands were flooded by dam construction several years ago. His group, known as the Displaced Persons of Picachos - after the name of the dam - has been demanding compensation for the land.

Roman Tirado had a weekly variety program on the local Fiesta Mexicana radio station in the Pacific coast port of Mazatlan. In past years, the movement had staged blockades and protest marches, which had resulted in some arrests.

Get Breaking News Delivered to Your Inbox

Sinaloa state prosecutors said Sunday that two men walked into the station Saturday and asked for Roman Tirado. The station is in a building that also houses the newspaper El Sol de Mazatlan.

One of the men waited outside the studio where Roman Tirado was broadcasting while the other assailant walked into the studio and shot him. He died at a local hospital.

The movement had become somewhat less active over the last couple of years, and Roman Tirado had ventured into other lines of business. But, at its height, the movement had reported receiving telephone death threats against its leaders.

The government gave houses to people whose villages were flooded by the construction of the Picachos dam, which started in 2006. However, the dwellings were tiny, shack-like structures.

Sinaloa Gov. Mario Lopez Valdez said Sunday that the killing would not go unpunished.

State prosecutor Marco Antonio Higuera said the killers used a 9-mm pistol in the crime, and that the station offices did not have security cameras that could have recorded the killing.

Attacks on radio stations are rare in Mexico, though print journalists and photographers have frequently been the victims of attacks and killings.

According to the New York-based Committee to Protect Journalists, 75 journalists and media workers have been killed since 1992; the vast majority worked as reporters or editors for print media.