Gastélum, who built a following through comedy and entertainment content on TikTok, was broadcasting live alongside two friends when the attack occurred.
According to reports, two men arrived at the location on a motorcycle. One of the suspects allegedly approached Gastélum and opened fire at close range before fleeing the scene with his accomplice.
The shooting unfolded while the livestream was still in progress, shocking viewers and adding to growing concerns over the safety of public figures and content creators in the country.
Local media reported that responding police officers initially believed the victim was a food delivery rider because he and the two companions were dressed in bright yellow jackets and carrying delivery bags. Authorities later confirmed that the deceased was César Gastélum.
Investigators have since launched a homicide investigation, but no arrests had been made as of the time of filing this report.
Police said forensic teams recovered cartridge casings from the scene and are reviewing closed-circuit television (CCTV) footage from nearby businesses to identify the attackers and establish the circumstances surrounding the killing.
Authorities have not disclosed a possible motive for the attack, and it remains unclear whether the influencer had received threats before his death.
Gastélum's killing is the latest in a string of violent attacks targeting social media personalities in Mexico.
In May 2025, 23-year-old beauty influencer Valeria Márquez was shot dead while livestreaming on TikTok from a beauty salon in Zapopan, in a case that drew widespread international attention.
Another Mexican content creator, Leobardo "El Gordo Peruci" Aispuro, was also killed in Culiacán in December, further highlighting the growing number of attacks involving influencers in the country.
Authorities say investigations into Gastélum's killing are ongoing, as detectives continue to gather forensic evidence and analyse surveillance footage in an effort to identify and apprehend those responsible.