Mexico City (CNN) -- At least 25 people were killed and more than 20 injured Sunday when a bus ran off a freeway and fell down an embankment in Guerrero state, Mexico, authorities said.
Nine of the dead were children.
The crash occurred just before 1 p.m. when the bus' brakes apparently failed while it was traveling over a steep incline, Guerrero state officials said. The bus plummeted 300 meters (983 feet) down the embankment.
The local government expressed condolences to the victims' families and pledged its support.
CNN's Catherine E. Shoichet and Kevin Gallagher contributed to this report.