The murders of two aides to Mexico City's Mayor Clara Brugada were meticulously planned by experienced gunmen, prosecutors said.

Mexican authorities have not said whether they see the shooting as targeted. It comes after a year of heightened political violence.

The victims were Mayor Clara Brugada's private secretary Ximena Guzman and adviser Jose Muñoz, and the assassinations have sent shock waves through the capital, considered relatively safe.