[1] While covering a shootout between drug traffickers of the Gulf Cartel and the Mexican Army in the streets of Matamoros on 5 November 2010, Guajardo Romero was caught in the crossfire and killed.

Guajardo Romero had left home earlier that day to cover the military-led operation targeting Antonio Cárdenas Guillén, one of Mexico's most-wanted drug lords, who was killed that afternoon.

[10] According to reports by the Mexican Army, a convoy of eight vehicles from the Gulf Cartel opened fire at several soldiers at around 11:00 a.m. in Fraccionamiento Victoria neighborhood in southern Matamoros.

[12][13] The incident was one among a number of armed confrontations and violent events that were registered that day in Matamoros, and led to the death of the drug lord Antonio Cárdenas Guillén, the former co-leader of the Gulf Cartel.

[20] The Ministry of National Defense (SEDENA) in Mexico released the following statement: "Generals, chiefs, army officers and air force personnel, together express their condolences of our supreme citizen commander Felipe Calderon Hinojosa, President of the Republic, towards the families of our fellow soldier and the journalist Carlos Guajardo-Romero, who both lost their lives in the line of duty.

"[11] Gregorio Salazar, director of International Federation of Journalists' Latin American office, said: "Danger is never far away for our Mexican colleagues who operate in one of the most hostile environment for media.

"[21] The Expreso de Matamoros newspaper issued an article speaking out against the drug-related violence in the state of Tamaulipas and asking for an extensive investigation for the death of their reporter.