Mexican police have been cracking down on notorious drug gangs over the past few months.

Thousands of police have been deployed to strategic locations in what is being called "operation shield" to stop the so-called "cockroach" effect, where a government crackdown in one place forces criminals to scurry to other locations.

The head of Mexico City’s security programme is determined to keep violence between cartels and vigilante groups out of the capital.

Some Knights Templar cartel leaders have been arrested and accused of killing hundreds of people.

Al Jazeera's David Mercer reports from Mexico City. 

Source: Al Jazeera