The 35-year-old fighter, whose father is legendary Mexican sportsman Perro Aguayo, was hit with a flying kick from former WWE star Rey Mysterio Jr. during a clash in Tijuana, Mexico on Friday (20Mar15), but the blow knocked him unconscious and left him slumped over the ropes on the side of the ring.

The brawl continued between other competitors for almost two more minutes before they realised Aguayo was seriously hurt and medics were called to the scene.

He was taken to a nearby hospital, where he was pronounced dead in the early hours of Saturday (21Mar15).

An initial autopsy revealed trauma to the neck and a cervical fracture as the cause of death.

Authorities have launched an investigation into the incident and are considering possible manslaughter charges.

Mysterio Jr., real name Oscar Gutierrez, took to Instagram after learning of his pal's death and paid tribute by sharing a photo of the pair.

He captioned it, "I had the privilege to share a ring for the first time with Hijo Del Perro Aguayo (Son of Perro Aguayo) in his debut as a professional wrestler & an Honor to be in the Ring with this great Legend for the last time! You will be missed Perro:: RIP Perro Aguayo Jr."