XALAPA, Mexico -- A newspaper reporter in the Mexican Gulf coast state of Veracruz who was enrolled in a government protection program for journalists was killed Tuesday along with two other men, one of his editors and a journalist advocacy group said.

Candido Rios Vazquez, a crime reporter for the newspaper Diario de Acayucan, was at least the ninth journalist slain this year in Mexico. More than 100 journalists have been killed in the past 25 years, according to the Committee to Protect Journalists.

"Every journalist in Mexico is a target now," Luis Chaparro, a freelance journalist in Ciudad Juarez, told "CBSN: On Assignment."

The State Commission for Attention and Protection of Journalists and Cecilio Perez Cortes, deputy editor at Rios' newspaper, said the reporter was in the federal government's mechanism for protection of journalists and human rights workers.

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Perez said Rios had been threatened repeatedly since 2012 by a former mayor of Hueyapan de Ocampo and had a panic button on his cellphone and a security camera at his home. Rios had just finished his work for the day around 3 p.m. and was on his way home, Perez said.

Rios apparently stopped alongside the highway in Hueyapan to speak with a former police inspector he knew who was also killed in the attack, Perez said.

Alex Chang, a Hueyapan councilman, said Rios died on the way to a hospital in Acayucan. Late Tuesday, the state prosecutor's office said it was investigating the killings.

Police and army patrol the streets of Acayucan, Veracruz state, Mexico, on Tue., July 11, 2017. AP

Mexico is now the world's deadliest country for journalists. The killing of the widely respected journalist Javier Valdez in the western state of Sinaloa in May brought renewed international attention to the issue.

Veracruz has been one of the most deadly Mexican states for journalists in recent years. Rios was the second journalist killed in the state this year. Newspaper columnist Ricardo Monlui was shot to death March 19 as he left a restaurant with his wife in the town of Yanga outside Cordoba.

Rios "started to do journalism because of the social struggle," Perez said. "He always protested against injustice." He did not have academic training, but learned on the job, the editor said.

The reporter started his career in a mountainous and largely indigenous area and advocated for farmworkers, women and migrants, Perez said. He founded The Voice of Hueyapan and later joined Diario de Acayucan, where he had worked for 10 years. Perez characterized Rios as "combative" when it came to causes he believed in.

Acayucan and surrounding towns are largely controlled by organized crime, making it a difficult place to do journalism, Perez said.

"We constantly receive threats," he said.

In a short audio message that Rios sent to Perez on Tuesday afternoon, Rios shouts to his boss over loud music about someone being wounded in a neighborhood. A minor story, Perez said. Rios signed off with: "May God take care of me. Good luck."