MEXICO CITY (AP) — A Mexican National Guardsmen shot and killed three fellow service members at a barracks over the weekend in the western Mexican state of Michoacan, where the government has surged security forces in the wake of recent high-profile killings.

A federal official confirmed the shooting Monday to The Associated Press, requesting anonymity because they were not authorized to discuss it publicly. The shooting, which wounded a fourth service member, was under investigation, the official said.

The suspect was in custody in Michoacan.

The shooting occurred Saturday hours after a car bomb exploded in Coahuayana, Michoacan, killing five people outside a local police station.

President Claudia Sheinbaum declined to give more details Monday.

The explosion and National Guard shooting came as the federal government has stepped up security activities in the state, sending in additional troops after two recent high-profile assassinations.

Last month, Sheinbaum sent 2,000 troops — on top of the 4,300 permanent ones and 4,000 in neighboring states – to Michoacan following the killings of an outspoken representative of the lime growers and a popular mayor standing up to the cartels.

At least three of the six drug cartels that the Trump administration designated as terrorist organizations — Jalisco New Generation, United Cartels and The New Michoacan Family — operate in Michoacan, in addition to a slew of homegrown armed splinter groups, some supported by the Sinaloa Cartel.