A five-ton elephant escaped from a circus and wandered onto a busy highway, where it was hit by a bus and died on Tuesday.
State officials say bus driver Tomas Lopez, 49, also was killed and at least four passengers were hospitalized after the pre-dawn collision in Ecatepec, just north of Mexico City.
Mexico State police spokesman Juan Sanchez said the elephant escaped from its cage at the Circo Union, but he declined to give any other details. He said officials were investigating.
The state-funded Notimex news agency reported that the elephant named Indra escaped as its keeper arrived to feed it, knocking down a metal door that led to the street and wandering through two neighborhoods before trying to cross the highway.
Small circuses have used the name "Circo Union" in Mexico and it was not immediately clear which was involved.
Last month, a 500-pound lion escaped from a private zoo owned by a local lawmaker in southern Mexico. The animal killed two dogs and a pig and attacked a woman and child on a donkey before it was sedated and caught.