From Mexico, CEOAFRICA.com gathered that over thirteen people were killed in separate attacks in the northern city of Matamoros in Tamaulipas state.

Sources disclosed that in two of the incidents, Mexican marines clashed with armed men, while in the third attack, members of rival gangs opened fire on each other.

Four men and one woman were killed in the first shoot-out between two rival groups on the main highway leading from Matamoros to the city of Reynosa.

The second gun battle happened just hours later on the same highway, when members of the Mexican marine force gave chase to an armed group and killed four of them.

Four more men were killed in central Matamoros after they opened fire on marines, officials said.

Local media said the weapons and munitions found at the scenes of the shoot-outs suggested they belonged to organized crime groups.

More than 77,000 people are estimated to have been killed in drug violence in Mexico since the then-president, Felipe Calderon, launched a war against the cartels in late 2006.