A state government in southern Mexico has found itself forced to play the role of middleman in an exchange of kidnap victims held by a gang of drug traffickers, and a band of angry citizens who seized a crime boss’s mother in an attempt to take back control of their lawless, opium-country town.

The government of the state of Guerrero sent police to spirit away María Félix de Almonte Salgado, the mother of drug gang boss Raybel Jacobo de Almonte, known as “El Tequilero”, after residents of the town of Totolapan got a kidnapped businessman back from the gang in return.

The strange standoff emerged after townspeople tired of kidnapping, extortion and killings formed an armed vigilante group and seized Mrs de Almonte Salgado and about 20 suspected gang members on Monday, then posted videos offering them in exchange for Isauro de Paz Duque, a construction engineer abducted the day before in an apparent extortion attempt.

Dozens of townspeople greeted a worried-looking De Paz Duque with cheers as he was released on Wednesday night in the town square. They then turned De Almonte Salgado over to state police, who apparently handed the humbly dressed woman over to the gang. The exchange was recorded on a video shot by Guerrero state human rights officials.

The state government publicly denied negotiating with the gang, but it was clear there had been contact.

“The state government intervened as a mediator, not a negotiator. We didn’t negotiate anything,” Governor Héctor Astudillo told local media.

But the state government’s willingness to act as an intermediary was unusual, especially since it announced last week that hundreds of police and soldiers were searching for El Tequilero in the mountains. Astudillo has also complained bitterly about the proliferation of such armed vigilante groups and the problems they pose.

“One way to see this is as an act of realism,” said Mexico City security expert Alejandro Hope. “Given the [government’s] inability to control these illegal groups, the best it can do is to mediate between them.”

State officials appealed to townspeople to release the 20 remaining drug gang suspects and promised they would be investigated and possibly charged for the reign of terror the gang has held over the town in recent years. Besides trafficking opium paste, the gang has kidnapped, killed and collected ransom and protection payments from residents.

The vigilante seizure of De Almonte Salgado appeared to violate an unwritten rule of Mexico’s drug war – that the families of drug gang bosses are generally viewed as off-limits. A recent attack on the home of the mother of imprisoned drug lord Joaquín “El Chapo” Guzmán occurred when the woman apparently wasn’t home.

Townspeople may have been emboldened by the fact that the Tequileros gang is one of several small, relatively ragtag gangs that dominate the mountains of Guerrero state, and not one of the top-level cartels. The leader’s mother was humbly dressed in a simple skirt and blouse and wore a long braid.

The only known public appearance of “El Tequilero” – his nickname is literally “the Tequila Drinker” – is a video showing him drinking with the town’s mayor-elect. De Alamonte mumbles inaudibly and has to be held up in a sitting position by one of his henchmen in that video.

Seldom have townspeople in Mexico won such a striking victory over drug gangs. The nearest example occurred in the neighboring state of Michoacán, where armed citizen groups rose up in 2013 and chased out a drug cartel.

Vigilante action has become increasingly common in Guerrero, but increasingly problematic. The vigilante groups now fight among themselves in some sections of the state, and some have allegedly allied with guerrilla or criminal groups.

Astudillo is just tired of it all. He said on Tuesday: “This is something that has to end – that every time somebody gets the idea into their head of kidnapping somebody, they kidnap them.”