An organization representing the mayors of Mexico is calling on the government to take action after two of its own were gunned down in brazen shootings not far from one another.

Ambrosio Soto Duarte and Domingo Lopez Gonzalez were both recently shot to death in bloody episodes that remain a mystery. According to the National Association of Mayors, over the last decade at least 40 local mayors have now been killed.

Violence Tied to Drug Trade 

The onslaught of violence can be traced to the government's crackdown on cartels, resulting in a rising level of violence across the entire region.

The mayor of the small town of Pungarabato, Soto Duarte was gunned down as he traveled with his security detail. Reports are two pickups stopped his vehicle and gunmen opened fire.

In the last tweet he posted, Soto Duarte talked of being threatened by members of organized crime and pleaded with authorities for assistance.

"They killed my cousin," he wrote. "I am being threatened. Now it is time to act, Mr. President. Tierra Caliente needs you."

The town of San Juan Chamula where Lopez Gonzalez was mayor has a long history of high tensions between the government and some of its poorest people. 

Several media outlets have reported the mayor was walking with some of those very residents when he was gunned down in broad daylight near the town's main square.

Four Others Injured

Four others were also killed in the deadly rampage, including the city's vice mayor, and another 12 were wounded. The state attorney general's office is now investigating.

"Violence will never be the way to resolve differences," said Chiapas Gov. Manuel Velasco. "The call is always to favor dialogue and understanding."

Members of the mayor's Democratic Revolution Party said Lopez Gonzalez had recently taken "special protection measures," after security patrols had abandoned the area.