Escalating fighting between factions of one of Mexico's most violent drug cartels has left at least 15 people dead this week in a gang stronghold shaken by gunfire, abductions and arson, authorities said Friday.

Security reinforcements have been sent to the northwestern state of Sinaloa -- the bastion of jailed drug kingpin Joaquin "El Chapo" Guzman and his sons -- where bodies have been abandoned in the streets.

The fighting follows the dramatic arrest on US soil in July of Sinaloa Cartel co-founder Ismael "El Mayo" Zambada, who claimed he had been kidnapped in Mexico and delivered into US custody against his will.

Zambada, 76, was detained along with Joaquin Guzman Lopez, a son of El Chapo, who is serving a life sentence in the United States.

The wave of violence in Sinaloa state capital Culiacan is believed to pit gang members loyal to El Chapo and his sons against others aligned with Zambada, who pleaded not guilty to a raft of charges in a New York court Friday.

"The rivalry stems from the events of July 25," Sinaloa state governor Ruben Rocha Moya said.

President Andres Manuel Lopez Obrador on Friday urged the warring factions to "act with a minimum of responsibility," urging them not to "harm innocent people."

He called on residents "to act with caution, but without alarmism," adding: "Hopefully soon complete normality will return to Culiacan."

The state prosecutor's office said that in addition to the 15 deaths, it was investigating 20 cases of suspected forced disappearances.

Authorities this week announced the closure of schools in some districts and the cancellation of Independence Day festivities due to the violence.

"There will be no celebration, neither public nor private," the governor said.

Many shops have closed their doors and supermarkets have experienced food shortages due to panic buying.

"Workers do not feel safe to go to their jobs, and business owners also face difficulties to operate in these adverse conditions," a statement from the National Chamber of Commerce said.

The United States on Thursday issued a security alert because of "reports of car thefts, gunfire, security forces operations, roadblocks, burning vehicles and closed roadways" in the vicinity of Culiacan.

"US citizens throughout Sinaloa should remain alert for potential violence throughout the state," it said.

Culiacan was the scene of violent riots by the Sinaloa cartel in October 2019 during an aborted security operation to capture one of El Chapo's sons, Ovidio Guzman, and again in January 2023, when the son was finally arrested.

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