Gunmen shot dead a journalist early on Sunday in the Mexican city of Iguala in the southwestern state of Guerrero, local authorities said, in what was at least the fourth murder of a reporter in the country this year, Reuters reported.

Pablo Morrugares of news website PM Noticias had gone to dine in an Iguala restaurant in the company of a police bodyguard when the unidentified assailants opened fire on them after midnight, Guerrero state prosecutors said in a statement.

The website also published an announcement about the killing on Facebook, as did the human rights commission of Guerrero.

The motive for the shooting was not immediately clear.

According to Reporters Without Borders, three other journalists had been killed in Mexico this year.