A ferocious gun battle between security forces and drug cartel gunmen raged late into the night on Thursday on the streets of the capital of Mexico's western Sinaloa state, after a failed police operation to capture one of the sons of jailed drug kingpin Joaquin "El Chapo" Guzman.
Mexican Security Minister Alfonso Durazo said late on Thursday that armed groups overpowered the security forces, prompting authorities to abandon their attempt to capture Guzman's son.
Durazo said the decision to release him was taken to protect lives.
Al Jazeera's Manuel Rapalo, reporting from Mexico City, said it seemed that the country's law enforcement authorities had been outgunned.
"They [the drug cartel] were using machine guns and high calibre ammunition against the police," Rapalo said, describing the violent street battle as like "images from a film".
TV network Milenio earlier reported that the attack was triggered by the arrest of Ovidio Guzman, one of the sons of Joaquin "El Chapo" Guzman who have assumed control of part of the cartel since their father was extradited to the United States in 2017.
Earlier on Thursday, sustained, heavy gunfire rocked the city of 750,000 people in a battle that left blazing vehicles strewn across the street and sent terrified residents running for shelter, according to AFP journalists at the scene.
Mexican television showed army and police forces under assault by gunmen armed with heavy machine guns.
President Andres Manuel Lopez Obrador said in a brief comment to journalists that his security cabinet was holding a meeting and would give details on the situation later.
Sources in the Sinaloa state government, speaking on condition of anonymity, said police officers had been wounded, but did not have details. Photos from the scene showed bodies lying in the streets and pools of blood.
Amid the chaos, an unknown number of inmates also escaped from the Aguaruto prison in Culiacan amid the chaos.
The state government said in a statement that it was "working to restore calm and order in the face of the high-impact incidents that have occurred in recent hours in various points around Culiacan".
It called on residents to "remain calm, stay off the streets and be very attentive to official advisories on the evolving situation."
The battle broke out in the afternoon near the state prosecutor's office, when masked attackers blocked traffic and opened fire, causing panicked drivers to abandon their cars in the middle of the street.
The fighting then spread to several other parts of the city.
Gunmen blocked roads and highways around the city into the evening, bringing the capital to a standstill.
The violence is the third serious incident in Mexico this week, after 13 police officers were ambushed and killed by drug cartel members in another western state on Monday, and a number of civilians were killed in an attack the following day.
The number of violent homicides in Mexico this year is on track to a record high, Al Jazeera's Rapalo said, heaping pressure on the government of President Lopez Obrador.
El Chapo, 62, was sentenced to life in prison in July for trafficking hundreds of tonnes of cocaine, heroin, methamphetamine and cannabis into the US over the course of a quarter-century.
However, his Sinaloa cartel remains one of the most powerful in Mexico.
Guzman's extradition unleashed an initial period of instability in the group, as his sons waged war with cartel cofounder, Ismael "El Mayo" Zambada, for control, leaving a trail of bodies in their wake.
But the situation appears to have evolved into a reluctant truce.
El Chapo, whose nickname means "Shorty", was rearrested in 2016 after a brazen prison escape - the second of his career.
He is considered the most powerful drug lord since Colombia's Pablo Escobar, who was killed in police action in 1993.
After being convicted in a New York court, he is now serving his sentence in the ADX federal maximum-security prison in Colorado.
Ovidio and his brother Alfredo have tried to fill their father's shoes, but anti-narcotics experts portray them as flashy party boys who have little ability to run the business side of the cartel.
Known as "Los Chapitos" or The Little Chapos, the pair were attacked in 2016 in a restaurant in the beach town of Puerto Vallarta.
They survived the attack, which the authorities called an attempted hit by rivals.
SOURCE: Al Jazeera and news agencies