Twenty people were shot and killed in Ciudad Madero town in northeastern Mexico in drug-related violence, officials said.
Six bodies were found in El Chipus neighbourhood of the town in Tamaulipas state, a spokesperson for the state attorney general's Office said on Friday.
Four more bodies were discovered in Francisco I. Madero neighbourhood, while six bodies were found in Talleres and Hidalgo areas, the spokesperson added.
A tip-off from an anonymous caller helped the police to find four more bodies in Lucio Blanco neighbourhood.
Tamaulipas state, bordering Texas, is a stronghold of the Gulf drug cartel, which is currently at war with former ally Los Zetas, a group of Mexican special forces deserters turned outlaws.