Two California teens in Mexico were fatally shot execution-style in an apartment Sunday morning, according to reports.

According to the San Diego Union-Tribune, Christopher Alexis Gomez, 17, Juan Suarez-Ojeda, and an 18-year-old man from Tijuana were tortured and murdered in Tijuana early Sunday after attending a barbecue Friday in Ensenada. Gomez’s cousin, Katheryn Garcia, said they were expected to return to the U.S. that evening but never did.

A motive in Sunday’s triple slaying isn’t immediately known. Punto Norte, a local news outlet in Tijuana, reported that investigators believe a group of armed men abducted the three teens, forced them to kneel, then shot them in the head. The three victims were reportedly found dead in their underwear in front of an apartment door at a complex in southern Tijuana.

Relatives reportedly contacted California authorities and searched for the teens over the weekend. It was Sunday night when they learned of the three bodies discovered at the Tijuana apartment complex hours earlier.

Gomez’s uncle went to a Tijuana morgue Monday and confirmed his nephew was one of the victims, according to the San Diego Union-Tribune.

“We’re all in disbelief that this happened,” Garcia tearfully told the outlet during a phone interview.

Gomez was reportedly born and raised and San Diego and had only been to Mexico once before. Relatives said Gomez and Suarez-Ojeda, who was dating Gomez’s sister, left home on Friday.

Garcia claimed they last heard from Gomez early Saturday, when he called his mother to tell them they were safe despite losing their cell phones.

Describing her late cousin, Garcia said, “I know how this story sounds, like something that people hear on the news: You go to Tijuana and this happens…But he was the most selfless, kindest boy ever…This shouldn’t have happened to him.”

[Featured image: Juan Suarez-Ojeda, Christopher Alexis Gomez/GoFundMe]