A gunman has shot dead two top aides of the mayor of Mexico City, Clara Brugada. The mayor's private secretary, Ximena Guzmán, and Brugada's adviser, José Muñoz, were killed on their way to work on Tuesday morning local time.

The personal secretary and an adviser to Mexico City’s mayor have been killed by gunmen on a motorcycle in a central neighborhood of the capital.

Mexican authorities have not said whether they see the slayings as targeted. They come after a year of heightened political violence.