The devastated family of an 18-year-old California college student who died after attending an off-campus fraternity event is demanding answers — including why no one apparently called 911 after the teen became unresponsive.

Anthony Joseph Blas, a student at California State University Fullerton, died shortly after midnight Sunday after he was dropped off unresponsive at the emergency department of St. Jude Medical Center, according to Fullerton police.

Hospital staff tried to save the teen, but he was pronounced dead shortly after arriving.

Now his grieving family is calling for a “complete and transparent investigation,” telling CBS News they are “deeply concerned that hazing may have played a role” in the tragedy.

“One of the most troubling questions for our family is why 911 was not called when Anthony was found unresponsive,” the family said in a statement to the outlet.

“We want to know what happened in the hours leading up to his death, who was present, when those present realized he was in distress, and why 911 was never contacted.”

Police said its preliminary investigation determined Blas had been attending a gathering at an “unaffiliated fraternity” near Associated Road and Milton Avenue before he was taken to the hospital.

Authorities said alcohol appears to have contributed to his death but stressed that investigators have not found evidence of foul play. Police said that “hazing is not considered to be a factor.”

Blas’ official cause and manner of death will be determined by the Orange County Sheriff-Coroner’s Office.

His family identified the fraternity allegedly connected to the gathering as Delta Chi and said they want authorities and university officials to fully examine whether hazing was involved.

The family emphasized that it was not accusing any particular person of responsibility.

“At this time, we are not making conclusions about the responsibility of any individual,” the statement continued. “We are asking for facts, accountability, and answers.”

Relatives also urged anyone who attended the gathering or possesses photos, videos, text messages, social media posts or other information from that night to preserve the material and turn it over to investigators.

Delta Chi had previously been separated from and had its recognition revoked by Cal State Fullerton over multiple alleged violations, including hazing or conspiracy to haze, illegal drug and alcohol violations and conduct threatening the health or safety of members of the university community, according to the Daily Titan, the university’s student newspaper.

The California Post reached out to Delta Chi for comment.

Blas’ uncle, Johnny Blas, shared a heartbreaking tribute to his nephew on Instagram after learning of his death.

“Anthony was such a loving boy,” he wrote, adding that he “cannot stop thinking about Anthony.”

“He just started college at Fullerton University in California. He was just 18 years old,” the grieving uncle wrote. “Love you Tio Johnny.”

Cal State Fullerton confirmed the student’s death in a statement to The Post and said it was providing support to the campus community.

“Our hearts are with the student’s family and the campus community during this incredibly difficult time,” the university said.

The school said counseling services were being offered to students and referred additional questions about the ongoing investigation to Fullerton police.

Police records cited by the Daily Titan show authorities were investigating a scene in the 2100 block of Teri Place early Sunday in connection with the case. Cal State Fullerton police also logged an investigation at the same location shortly afterward and Fullerton police confirmed the agencies were investigating the same incident, according to the outlet.