At least nine people were killed on Friday by an armed group in the northwestern Mexican state of Sinaloa while in the southeastern resort city of Acapulco four heads were found abandoned in a van.

The nine victims of Sinaloa were practically shot with two types of rifles, the AK-47 and AR-15, at dawn in the Agustina Ramirez community, according to the state attorney general's office.

Preliminary investigations conducted by the office, the armed group arrived early morning at the crime scene. They tied the victims and then killed them.

Furthermore, on Thursday night, the heads of four people were found in Acapulco inside a van abandoned in a street near the city center. Inside the vehicle, local police found human remains and a message from an organized crime group, authorities said.

More than 47,000 people have been killed in drug-related violence in Mexico since President Felipe Calderon launched the " war against organized crimes" in 2006.