A fire at a discount store in northwestern Mexico has killed at least 23 people and injured at least 11, the state governor said on Sunday.

The fire ripped through an outlet of Waldo's, Mexico's chain of dollar-format stores, on Saturday in Hermosillo, the capital of Sonora state, in northern Mexico.

Governor Alfonso Durazo warned that some of the victims are children.

"The explosion that occurred in the Waldo's store in the center of Hermosillo has left a profound sadness in all Sonorenses," Durazo said during a video briefing published on social media.

"At the moment, there are 23 people dead and 11 injured who are being treated in different hospitals in the city. Sadly a number of the victims we've found were minors," Durazo added.

The governor said he ordered an "exhaustive and transparent investigation to clarify the causes of the fire, and determine who is responsible."

Toxic gas ramps up death toll

Most of the 23 deaths appeared to have been from inhalation of toxic gases, said Gustavo Salas, the state's attorney general, citing its forensic medical service.

"My heartfelt condolences to the families and loved ones of those who lost their lives," President Claudia Sheinbaum said in a post on X, adding that she had directed support teams to be sent to help victims' families and the injured. 

Sonora's Red Cross said its 40 staff and 10 ambulances joined in the effort, making six trips to the hospital.

What else do we know about the fire at discount store in Mexico?

City officials said the fire was most likely not a targeted attack.

"At this time, there is no indication that the fire was intentionally set," the prosecutor reported, adding that "the investigation is looking into a transformer located inside the store."

The fire occurred in mid-afternoon when the store was full of customers shopping ahead of the Day of the Dead celebrations. 

Edited by: Karl Sexton and Darko Janjevic