Firefighters work on a burned bus in the highway bewteen Guadalajara in Jalisco state and Leon city, in Guanajuato State, Mexico, on May 01, 2015. More than a dozen vehicles were set on fire on Friday across Guadalajara, Mexico's second biggest city, while a drug gang and authorities clashed in another part of Jalisco state. Authorities have not said who was responsible for the violence, but it came amid an escalation of violence by the Jalisco New Generation Drug Cartel, which killed 20 police officers in two ambushes in March and April. AFP PHOTO/STR (Photo credit should read STR/AFP via Getty Images)
