The bound and burned bodies of eight men were found in the central Mexico state of Queretaro, prosecutors said on Sunday.
The still-unidentified bodies were discovered in the back of two burned-out trucks on a rural road late on Saturday, state and federal prosecutors said in a statement.
The victims' hands were tied behind their backs with wire, and they were apparently killed elsewhere.
Also on Sunday, in the northern state of Chihuahua, officials reported that gunmen killed four police officers in a series of attacks on patrol cars in the border city of Ciudad Juarez on Saturday.
State police spokesman Fidel Banuelos said the first attack killed two brothers who were patrolling together but worked for different agencies.
Police and prosecutors said two more officers were wounded in two other attacks.
There was no immediate information on possible motives. Nearly 2,500 people have died in drug-related violence this year in the city across from El Paso, Texas.