The Mexican military has killed 19 suspected members of the Sinaloa cartel, the Ministry of National Defense said, after they came under attack in the northwestern state.

More than 30 gunmen fired at soldiers in the Sinaloa capital, Culiacan, on Monday resulting in a shootout in which the cartel members were killed, according to a statement from the ministry on Tuesday.

Intra-cartel violence has intensified following the arrest in July of the Sinaloa cartel’s co-founder Ismael “El Mayo” Zambada Garcia, who is now on trial in the United States.

The ministry said the cartel members killed on Monday were presumed to be linked to Zambada’s faction.

One local cartel leader was arrested during the shootout, and identified by the authorities as Edwin Antonio “N”.

The other gunmen fled the scene after troops returned fire. Seven vehicles and nearly 30 firearms, including machine guns, ammunition, and military-style vests and helmets were seized.

On July 25, the US announced it had arrested 76-year-old Zambada and 38-year-old Joaquin Guzman Lopez at an airport near El Paso, Texas. The latter is the son of Joaquin “El Chapo” Guzman, another co-founder of the drug trafficking syndicate.

Zambada accused Guzman Lopez of kidnapping him and handing him over to US law enforcement.

“El Chapo” has been serving a life sentence in the US for drug trafficking since 2019.

In September, Zambada pleaded not guilty to drug trafficking, murder and other charges in a New York court.

Guzman Lopez pleaded not guilty to drug trafficking and other charges in a Chicago federal court in July.

Gang violence in Sinaloa has intensified since early September with about 200 people killed and more than 300 others believed to be missing, according to official data.

Spiralling violence, much of it linked to drug trafficking and gangs, has seen more than 450,000 people murdered in Mexico since 2006.