At least five people were killed and seven were wounded when gunmen opened fire on a group of community self-defense members gathered Monday, July 22, on a plaza in the western state of Michoacan, authorities said, according to The Associated Press.

Michoacan state prosecutors' spokesman Alejandro Arellano said about 300 masked community vigilantes wearing similar T-shirts arrived at city hall in the town of Los Reyes and announced they would take over policing the town.

Minutes later three assailants opened fired on the crowd, killing three members of the self-defense group, a police officer and a passer-by, Arellano said.

Wearing T-shirts that read "For a free Los Reyes" on the front and "Auto-defense group" on the back, the vigilantes had held a news conference to say they would clear the town of criminals and asked to talk to the mayor. They accused local police of having links to organized crime and also asked for federal police and soldiers to be sent to the town.

Self-defense squads have been forming in recent months in Michoacan and in neighboring Guerrero state by people who say they are fighting violence, kidnappings and extortions carried out by drug cartels. But concerns have surfaced that the vigilantes may be violating the law, abusing the rights of people they detain, or even cooperating with criminals in some cases.

In Michoacan, the vigilante groups appeared in February and clashes between them and the Knights Templar drug cartel have been intensifying.