Taekwondo instructor ‘Master Lion’ accused of killing 7-year-old student and his parents

Police have yet to reveal a motive

Australia Taekwondo Academy Killings (AAP Image)

A taekwondo instructor killed a 7-year-old student at his academy and the boy's parents before going to a Sydney hospital, police have said.

Kwang Kyung Yoo, owner of the Lion’s Taekwondo and Martial Arts Academy and known to his students as Master Lion, will eventually be charged with three counts of murder, Homicide Detective Superintendent Daniel Doherty said.

The crimes were discovered after the instructor admitted himself to a hospital on Monday night suffering “stab wounds or slash wounds” to his chest, stomach and arms, Doherty said. He said the man told police he had been attacked in a supermarket carpark.

Police allege Yoo killed Min Cho, 41, and her son at his academy after a class on Monday before driving to their home, where he killed Cho’s husband and the boy’s father, Steven Cho, 39.

Police did not officially release the victims’ names, but the adults were identified in media reports.

Police discovered the bodies Tuesday and arrested Yoo at the hospital.

Police discovered the bodies Tuesday and arrested Yoo (AAP Image)

Police have yet to reveal a motive. They knew all four were born in South Korea and the slain boy had been a regular taekwondo student.

“We’re still establishing what other connections or ... what other relationships may have been or may not have been,” Doherty said.

Unnamed police sources told media the mother and son were strangled. The father was stabbed to death. Police have yet to determine how Yoo’s injuries were inflicted.

“It’s not only tragic in the circumstances, but the consequences were cataclysmic. We’ve just lost three people from one family who’ve had their lives taken away,” Doherty added.

Yoo drove the woman’s BMW sedan from the academy to the family home and then to the Sydney hospital, media reported.

He underwent surgery for his wounds and understood that he was under arrest, Doherty said.

"There was no warnings, from what we have gathered so far. It was out of the blue. It wasn’t something that was forewarned or planned,” Doherty said.

The maximum penalty for someone convicted of murder in New South Wales state is life imprisonment, with a standard non-parole period of 20 years for the murder of an adult and 25 years for the murder of a child.