Mexico's president has defended freeing drug kingpin Joaquín "El Chapo" Guzmán's son soon after his arrest.When Ovidio Guzmán López was seized at a house on a judge's warrant in the city of Culiacán, cartel gunmen fought street battles with security forces.At least eight people were killed and 16 wounded, the authorities say, with vehicles left burning in the streets.President Andres Manuel Lopez Obrador said the decision to cancel the arrest on Thursday had saved lives.Senior security officials had decided on his release, the president said at a news conference. "The officials who took this decision did well," he said."The capture of a criminal is not worth more than people's lives."A lawyer for the Guzmán family appeared before journalists and described the president as "human" and "Christian". He had decided "not to cause Ovidio harm", Jose Luis Gonzalez Meza said.There was no negotiation to free him, he added.Mr López Obrador was elected on a platform of cracking down on Mexico's drug cartels, and has tasked the National Guard, a new security force, with fighting the dealers.Under El Chapo's leadership, the Sinaloa cartel was the biggest supplier of drugs to the US, officials say.The kingpin was jailed earlier this year, and Ovidio Guzmán Lopez is one of several brothers with a hand in running the cartel.Thought to be in his twenties, he is accused of drug trafficking in the US.

What happened in Culiacán?

A patrol of National Guard militarised police came under intense fire from a house on Thursday afternoon, Security Minister Alfonso Durazo said.The security forces fought back and found Mr Guzmán, but were then surrounded by gunmen and forced to retreat.Defence Minister Luis Cresencio Sandoval told reporters the operation had been "badly planned".Five cartel members and a National Guard policeman are among the dead, he said.Fighters also attacked security forces in other parts of Culiacán and bodies were seen on the streets.Witnesses described scenes of panic in the city, a stronghold of the Sinaloa cartel, as families with small children fled from gunfire. Trucks were set alight in the streets to block roadsFootage on social media showed a pick-up truck with a machine gun mounted on the back, in scenes reminiscent of a war zone.Fifty-one inmates escaped from Aguaruto prison during the disorder.