Nine people were killed and at least ten injured after a bus and a double tractor-trailer collided on a highway in the northeastern Mexican state of Tamaulipas, media reported citing the state Attorney General's office.The incident involved a bus transporting workers from the Invamex assembly plant and a tractor-trailer carrying grain and occurred on Thursday on the Reynosa-Matamoros highway, the state AG's office told Efe on Friday.So far, only five of the victims have been identified. The AG's office also said the exact number of injured is not known, although between 18 and 20 people are thought to have been hurt.According to local media, the driver of the truck came across the median line into the oncoming lane and hit the bus.