Violence intensified in Mexico before national elections in June.
Soldiers stand guard on May 2 as smoke rises after a military helicopter was shot down in the town of Villa Purificacion. At least six soldiers died in the attack.
(Yuri Cortez / AFP/Getty Images)
Soldiers stand guard on May 3 as vehicles involved in a clash are removed from the site in Villa Purificacion.
(Yuri Cortez / AFP/Getty Images)
A policeman tries to control traffic next to a burned dump truck in Guadalajara, Mexico, on May 1.
(Refugio Ruiz / Associated Press)Advertisement
Firefighters work on a burned truck on the Guadalajara-Autlan highway.
(Hector Guerrero / AFP/Getty Images)