April 2015, around 3 p.m. on a winding pass in Western Halisco State, Mexico.

Blue skies in a burning sun and a road carved between two mountainsides.

A convoy of police officers is snaking along the SunKist Highway towards Guadalajara,

the country's third largest city.

These are no ordinary beat-cobs. They're elite troops of the

Fuesa Unica Helisko, the state's top men. As the convoy rounds occur in the road, just outside the town of San Sebastian deloesti, there it is, a barricade of burning vehicles, an impassable of inferno.

The cops are blocked in, no way out. Then, from above, a deafening explosion of fire,

high-powered machine guns and grenades raining down on the trucks from either side of the valley.

No chance to fight back.

Those who climb out of the vehicles are cut down by gunfire.

Those who can't have burned alive. Within moments it's over.

Fifteen cops are dead, five are wounded. The gunman escape unhurt.

It's the deadliest attack on state forces since 2010, a new grim

chapter in a Mexican drug war that to date has claimed 100,000 lives.

Its brutal episodes are often met with indifference by a jaded population

that's had to cope with daily threats of death for years.

This slaughter, however, shocks the nation.

Shootouts with criminal groups are common, says security expert Alejandro Hope.

What is rare for government forces to come off worse than the criminal groups.

Within hours, Harysco officials have their purps, the cartel de Halsco-Nue-Herecion,

C-J-N-G for short.

A Cinalloa Splinter Cell led by a madman named El Mincho.

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