In June, Reyes ran in the municipal elections of Emiliano Zapata, where he resided.
"The body of a man identified as Manuel 'N' was found. He had an ID card of an employee of the online media portal Portal Morelos. The death was caused by gunshot wounds to the head," the prosecutor's office said on Facebook.
So far there is no information about the number of attackers, according to the prosecutor's office, though at least one person fired at the journalist from close range.
Local media reported that Reyes was finishing lunch at a hotel when two men drove up to him on a motorcycle and opened fire. Two 9 mm casings were found at the scene of the crime, according to reports.
This is the sixth murder of a journalist in Mexico since the beginning of the year.