Vigilantes in Mexico have clashed with soldiers deployed in the western state of Michoacan to disarm the groups, who last week launched an offensive against the Knights Templar drug cartel.
Most groups have ignored a government order to lay down their weapons.
In the town of Antunez, they say soldiers shot dead at least three people from the community, including an 11-year-old girl.
Vigilante groups have now taken control of large areas of Michoacan state.
There is a strong police and military presence in the town of Apatzingan, considered the stronghold of the Knights Templar cartel.
Most businesses around the town are closed in a form of self-imposed curfew, says the BBC's Will Grant in Michoacan.
"There is no law here. The decisions are taken here in the mountains, in the hideouts of the Knights Templar leaders," Apatzingan Catholic priest Gregorio Lopez told the BBC.
"They are the ones who decide. Here the public institutions are mere puppets," said Father Lopez.
On Monday, Interior Minister Miguel Angel Osorio Chong had a meeting with the state governor in the regional capital, Morelia, and announced the deployment of federal troops to quell the violence.
Mr Osorio Chong said the vigilante groups should either join the police force or disarm.
Soldiers and marines have moved into towns seized in the past week by the vigilantes - Nueva Italia, Paracuaro and Antunez.
Leaders of the "self-defence groups" have given contradictory statements as to whether they would disarm.
Some of them initially indicated that they would follow the government orders, but most of the groups have now rejected orders to disarm.
"We're here to the death, all of us," warned Estanislao Beltran, who heads a vigilante group in the town of Tepalcatepec.
New Generation cartel
The vigilante groups first emerged in early 2013 as response to the violence perpetrated by the drug cartel, which ranges from extortion to kidnappings.
Local citizens said that they had no choice but to arm themselves as federal troops failed to guarantee their security.
"How does the federal government imagine that we would lay down our arms when they haven't detained a single leader of the Knights Templar? How is that fair?" asked a vigilante leader in Michoacan.
"It's illogical. Because if we're left without weapons, they will immediately come and kill us."
The Knights Templar, which controls much of the methamphetamine trade to the United States, says the vigilantes have sided with their rivals of the New Generation cartel, from neighbouring Jalisco state.
The "self-defence groups" fiercely deny involvement with any criminal organisation.