César Cuauhtémoc González Barrón, better known as lucha libre’s masked legend Silver King, passed away this evening after suffering what many believe to be a heart attack while competing in the ring. He was 51-years-old.

Silver King is the son of the iconic Dr. Wagner, and the younger brother of three-time AAA Mega Champion Dr. Wagner Jr. At the time of his death, he was competing for a promotion called Lucha Libre World in Camden, London.

According to PWInsider, King delivered a clothesline to Juventud Guerrera and went down to the mat to make a cover, but did not get back up. Officials and other wrestlers eventually hit the ring to try and revive him, and apparently a defibrillator was even used at one point. He was taken to the hospital, and it was later announced by both Sexy Star and the Lucha Blog Twitter account that King had passed away.

The third generation star had been wrestling full-time for more than 32 years, competing for CMLL, UWA, All Japan, IWA: Japan, WCW, New Japan and AAA. During his time in New Japan he portrayed the third generation of the Tiger Mask character, taking over the role from Eddie Guerrero.

King is a former AAA World Tag Team Champion, All Japan Jr. Heavyweight Champion, a 330-day CMLL World Heavyweight Champion, two-time CMLL World Tag Team Champion and CMLL World Trios Champion.