Hundreds of armed vigilantes set up traffic stops and searched houses in Tierra Colorada, a town on a major highway between Mexico City and Acapulco, about 12 miles from Acapulco in in the southern coastal state of Guerrero.
The group claims the town's ex-security director Oscar Ulises Valle, who was one of 12 police and six civilians detained, was involved in the killing of leader Guadalupe Quinones Carabajal, 27.
According to the Global Post, the self-defense group handed the captives over to the Guerrero Attorney General's Office Tuesday in exchange for a promise they will be investigated for alleged connections to the drug trafficking group, Union of Peoples and Organizations of Guerrero State.
"We have besieged the municipality, because here criminals operate with impunity in broad daylight, in view of municipal authorities," said vigilante group spokesman Bruno Placido Valerio. "We have detained the director of public security because he is involved with criminals and he knows who killed our commander."
The New York Post reported that some vigilantes fired shots at a group of tourists from Mexico City who refused to stop at a checkpoint. One person was slightly wounded.