They arrived carrying rifles, machetes and sticks, their faces covered with ski masks and scarves.
About 300 armed civilians poured into the small town of Chilapa, in the troubled state of Guerrero, on the afternoon of May 9, a Saturday, hitting people and breaking into their houses in a seemingly systematic rampage.
Behind them came white pickup trucks loaded with young men sporting high-caliber weapons. Cellphone video taken by residents shows armed people in civilian clothing threatening people on the streets.
"At first we thought that they might be community police," said Felipe Nava Reyes, 24, a truck driver who was in the center of town when they arrived. Community police and self-defense teams are common in Guerrero and the neighboring state of Michoacan.
"But then on Sunday, they started to take people."
The armed men and women who rode into town that Saturday were members of a criminal gang known as Los Ardillos, or the Squirrels. What unfolded over the next five days was a narco standoff between them and a rival drug gang, Los Rojos, or the Reds, that usually controls Chilapa, according to witnesses, social media and local news reports.
As so often happens in Mexico, the ordinary residents of the town were caught in the middle.
Nava's brother Alexandro, 21, who is also a truck driver, disappeared Sunday evening. He had been trying to pass a checkpoint set up in town by the armed occupiers, said his older brother, who had been in touch with him on an instant-messaging app.
"The last time he was on WhatsApp was at 8:15 that evening. I called and called but haven't been able to reach him," Nava said.
By the time the outsiders left on Thursday, at least 16 people, all of them male and aged 14 to 30, were taken from the streets of Chilapa, according to families of the missing.
But residents believe that nearly twice that number may have disappeared and that their families have been too fearful to report them missing. The state attorney's office in Guerrero said it was looking into at least 11 cases and considering four more.
Chilapa was locked down for five days by its occupiers despite the presence of the Mexican army, the gendarmerie (a national elite police force) and municipal and state forces, none of which intervened. Cellphone video shows residents admonishing soldiers for just standing around, and residents said that when they asked soldiers and police to act, they were told that the forces were under orders to just observe.
Schools and businesses were closed, and the town's famous Sunday market didn't open. The mayor fled.
Nava said that after his brother's disappearance, he went to speak to the armed people at the checkpoint.
"They said they didn't know anything, that they were following orders to take people on black motorbikes," he said.
Townspeople believe the Ardillos gang members were searching for the chief of the Rojos, but also picked up anyone on a motorcycle who they thought might be working for the Rojos.
Chilapa and the surrounding region had seen violence or disappearances before. In January, 10 bodies and 11 decapitated heads were found in clandestine graves near Chilapa. In late November, 11 bodies were discovered in the area.
The smiling face of Ulises Fabian Quiroz, who was a candidate in next month's midterm elections, still adorns posters around town, promising order and peace.
He was killed less than three weeks ago, ambushed by armed men on a highway. Graffiti accuse a rival party of complicity in his death.
Since 2008, 24 political candidates have been slain in Mexico, with Guerrero accounting for more cases than any other state.
And not just the politically active have suffered.
Jose Diaz Navarro, 52, a teacher, said his brothers Hugo, 32, and Alex, 45, disappeared in November after they were stopped by armed men while heading home from work at a construction project.
"Organized crime has been operating here for at least eight or nine years. Since then there have been armed men on the streets saying that they represent criminal groups, narcos, threatening and extorting people in the market and taxi drivers. And it's just gotten worse," Diaz Navarro said.
He and his brother Mario spoke as they sat in the front room of their small house off the main drag in Chilapa. "The only thing that these elections are going to define is what criminal group governs us," Mario Diaz Navarro said.
Chilapa is less than an hour's drive from the rural teachers school in Ayotzinapa that was home to 43 students who were abducted on Sept. 26 from the city of Iguala.
The federal government says they were detained by local police, who then handed them over to a criminal gang that killed them. The remains of just one of the students have been identified, and the rest are still missing, despite the unearthing of about 100 bodies in clandestine graves around Iguala over the last six months.
The disappearance of the students caused a national and international scandal, and threw yet more light on the corruption of Mexico's security forces, the collusion between them and organized crime, and the impunity enjoyed by those who kill and "disappear" people.
The standoff in Chilapa eventually ended when the occupiers came to an agreement with the state authorities that the leader of Los Rojos would be arrested. The outside gang has threatened to return this week if the authorities don't honor their promise.
"People here are going to lock themselves away with their Virgin statues and candles," Jose Diaz Navarro said. "Everyone is so afraid."