Factbox: Major incidents in Mexico's drug wars

Heavily armed fighters surrounded security forces in a Mexican city and made them free one of jailed drug lord Joaquin "El Chapo" Guzman's sons, after his capture triggered gunbattles and a prison break that sent civilians scurrying for cover.

The incident surrounding the arrest of Ovidio Guzman was on a scale rarely seen in Mexico's long drug wars and raised pressure on President Andres Manuel Lopez Obrador, who took office last December promising to pacify the country.

Here are some of the most significant moments in more than a decade of Mexico's drug wars:

Sept 15, 2008 - Suspected members of the Zetas drug gang tossed grenades into a crowd celebrating Mexico's independence day in the western city of Morelia, killing eight people and wounding more than 100.

Jan 31, 2010 - Suspected cartel assailants killed 13 high school students and two adults at a party in Ciudad Juarez, across from El Paso, Texas.

Aug 25, 2011 - Masked gunmen torch a casino in the northern city of Monterrey, killing 52 people, most of them women. Then President Felipe Calderon declared three days of mourning and demanded a crackdown on drugs in the United States, the main market for Mexican narcotics.

May 4, 2012 - The bodies of nine people were found hanging from a bridge and 14 others found dismembered in the border city of Nuevo Laredo.

Oct. 7, 2012 - Mexican Marines killed the leader of the Zetas drug gang, Heriberto "The Executioner" Lazcano, in the northern state of Coahuila. His body was snatched from the funeral home by armed men.

Sept. 26, 2014 - Forty-three student teachers disappeared after they were abducted in the state of Guerrero by police who the government said handed them over to a gang involved in heroin trafficking. Authorities definitively identified the remains of only one of them, and the incident has never been fully explained.

April 6, 2015 - Fifteen police were killed in an ambush in Jalisco state during weeks of violence that claimed the lives of more than two dozen officers and culminated in the shooting down of an army helicopter. Authorities blamed the violence on the Jalisco New Generation Cartel (CJNG), formerly underlings in El Chapo's Sinaloa Cartel who turned on their masters.

July 11, 2015 - El Chapo, Mexico's most notorious drug lord, broke out of a high-security prison for the second time, escaping in a tunnel built right under his cell. He had previously bribed his way out of prison during an escape in 2001.

Jan 8, 2016 - Security forces recaptured El Chapo in a pre-dawn shootout and chase through drains in his native Sinaloa.

Sept 6, 2018 - Prosecutors said the bodies of at least 166 people had been found in the state of Veracruz, an important trafficking route for drug gangs moving narcotics toward the U.S. border.

Oct. 14, 2019 - Suspected CJNG hitmen shot dead more than a dozen police in an ambush in Michoacan, in one of the bloodiest attacks on security forces since President Lopez Obrador took office in late 2018. The next day, soldiers killed 14 suspected gang members in neighboring Guerrero.