Shocking video shows the moment Mexican politician was assassinated after an electoral debate (Watch)

A man running for the Chamber of Deputies in Mexico city's Piedras Negras was assassinated and it was caught on CCTV.

Fernando Puron Johnston had served as a mayor of Piedras Negras, but he had his eye on Mexico’s Chamber of Deputies, the equivalent of their "Congress", and the election is to be held on July 1, 2018. Sadly, he didn't live to see the election day.

At the end of an electoral debate held in the city of Piedras Negras in Coahuila, Mexico, Fernando Johnston was assassinated by a hitman who approached him from behind and fired a single shot at his head at point-blank range.

He was killed last Friday evening after participating in a political debate against his two opponents. According to reports, Fernando Johnston was leading in the polls and had an anti-narco policy platform.

More than 20 candidates have been reportedly killed ahead of this year's elections in Mexico.

Watch the shocking video below.