An armed attack on a group of off-duty police in northwestern Mexico killed an officer and a journalist who was speaking to them at the time, authorities said Monday.

Three suspects were detained following the shooting on Sunday night in San Luis Rio Colorado in Sonora state near the US border, local mayor Santos Gonzalez Yescas said.

According to the Sonora public prosecutor's office, police came under fire while talking to journalist Jesus Gutierrez Vergara from the Notiface news site.

Three officers were wounded and one was killed along with Gutierrez Vergara, a neighbor whose death prosecutors described as collateral damage.

At least four other journalists have been murdered in Mexico so far this year, according to the media rights group Reporters Without Borders (RSF).

Authorities are investigating whether the deaths are related to their media work.

Mexico is considered one of the most dangerous countries in the world to be a reporter.

Since 2000, more than 150 journalists have been murdered in the country, according to RSF.

Most crimes against journalists go unpunished.

More than 420,000 people have been killed across Mexico since the government deployed the army to fight drug cartels in 2006.