MEXICO CITY — About 100 armed men attacked a group of journalists and robbed them of their equipment in Mexico's troubled southern state of Guerrero, authorities and media reports said Sunday.

The newspaper La Jornada said two of its employees were among seven journalists accosted while covering a security operation in San Miguel Totolapan on Saturday.

They were traveling in two SUVs when they were intercepted by the gunmen and relieved of cameras, cellphones, personal effects and one of the vehicles.

The attackers roughed up some of the journalists and threatened to burn them and the SUVs before letting them leave in the second vehicle, La Jornada reported.

Mexico is one of the world's deadliest countries for journalists, with at least 40 killed due to their work since 1992 according to the Committee to Protect Journalists.

The federal Attorney General's Office said in a statement that its Crimes Against Freedom of Expression division has opened an investigation into Saturday's incident, which took place on the highway between Ciudad Altamirano and Iguala.

Guerrero state has been a hotspot of drug cartel violence in recent years. Iguala is the city where 43 teachers' college students disappeared in 2014 after being detained by local police.

"Guerrero is one of the most dangerous places for the exercise of journalism in Mexico, so it is necessary that authorities establish the necessary conditions to guarantee that journalists' work can be carried out without any kind of obstacle from public servants or private citizens," the country's National Human Rights Commission said in a statement.