Mexico City – At least 10 bodies were dumped at various locations in the southern Mexican state of Michoacan, officials said.
The bodies were found on Sunday, a day after eight other bodies were dumped on the streets of Lazaro Cardenas, a port city in Michoacan.
The bodies were left on different roads in the regions of Jiquilpan and Sahuayo, near the border with Jalisco state.
The victims were all males whose hands and feet had been bound, and messages were left with the bodies stating that the killings were a settling of scores.
Four of the victims have been identified as Hugo Castañeda Ruiz, 32, Refugio Lopez Valdovinos, 18, Mario Gabriel Macias Gallardo, 19, and Luis Miguel Miranda Avalos, 23.
Miranda Avalos was released from prison a few days ago after being charged with robbery.
Most of the victims were shot with .38-caliber "super" pistols, officials said.
Eight bodies were found on Saturday at different locations in Lazaro Cardenas, where criminals also left threatening messages for a rival gang.
The victims in Lazaro Cardenas were bound and shot execution-style.
The violence in Michoacan is blamed on the break-up of La Familia, which was founded in 2006 and was considered one of Mexico's most powerful drug cartels.
La Familia Michoacana's members have formed rival gangs that are battling for control of the area.
The La Familia faction led by Jesus Mendez is battling the faction led by Servando Gomez and Enrique Plancarte, who formed the Los Caballeros Templarios gang in March, journalists from Michoacan told Efe.
La Familia Michoacana began unraveling after the death in a shootout with Federal Police officers in late 2010 of Nazario Moreno Gonzalez, known as "El Chayo."
Los Caballeros Templarios was apparently behind the 18 killings over the weekend in Michoacan.
A total of 15,270 people died in drug-related violence in Mexico last year, and nearly 40,000 people have died since President Felipe Calderon declared war on the country's cartels shortly after taking office in December 2006.