Two Federal Police officers died and 21 were injured when a chartered bus carrying them back to their duty station after several days leave flipped over on a road in the central state de San Luis Potosi, Mexican authorities said Friday.

A Federal Police source told Efe that the incident occurred Thursday when the officers were traveling from Mexico City to Nuevo Laredo, a city in the northern border state of Tamaulipas.

The bus driver lost control of the vehicle, apparently for "climatological reasons," at Kilometer-59 (Mile-37) of the Matehuala-San Luis Potosi highway, he said

The bus skidded off the highway and overturned.

"Unfortunately two of our colleagues lost their lives, 21 were injured," as were the driver and conductor of the bus, the source said.

About the condition of the injured, he said that all have slight bruises but "nothing that is life-threatening."

Federal Police provide backing for local security forces in several conflicted regions of the country such as Tamaulipas, a state bordering Texas that is afflicted by the violence of criminal organizations like Los Zetas and the Gulf and Sinaloa drug cartels. EFE