Vigilante groups in the troubled Mexican state of Michoacan have entered a stronghold of the Knights Templar drug cartel, occupying the main square.
Hundreds of vigilantes, backed up by armoured vehicles and troops, arrived in Apatzingan on Saturday.
They have also set up roadblocks around the city, in western Mexico.
The cartel controls much of the drug trafficking in the area, carrying out killings and kidnappings and extorting money from local people.
Vigilante leaders, who have joined the official security forces, and the army have been searching house by house for leaders of the Knights Templar.
Some arrests have been made, including the brother of one of the organisation's top leaders, according to local reports.
The vigilantes "will be in charge of security in Apatzingan", Michoacan deputy government secretary Fernando Cano told AFP news agency.
In the beginning of January, the "self-defence groups" launched an offensive against the Knights Templar gang, taking over several municipalities in Michoacan.
On 11 January, they also occupied the central square of Apatzingan, where the cartel's command is based.
But there were reprisals, with arson attacks against local businesses.
The new operation began just before 11:00 local time (17:00 GMT) on Saturday.
The vigilantes, federal police and soldiers walked unchallenged into the centre of Apatzingan.
Checkpoints have been set up along several access routes to the city "to check who goes in and out," said vigilante leader Estanislao Beltran.