McMahon, 25, was identified by family members as the victim in the early Friday morning shooting, said The Hollywood Reporter.
Authorities reached the 3600 block of Yorkshire Road at 2:19 am on Friday, where deputies found the male victim with gunshot wounds, according to a Los Angeles County Sheriff's statement.
At 4 pm on Friday, the Sheriff's Dept stated that a suspect in the shooting had been identified as a man, 25, who "was located inside his vehicle, with what appears to be a self-inflicted gunshot wound." The suspect's name was not disclosed then.
"We are heartsick about this tragedy - our thoughts and prayers go out to his family and to all that knew and worked with him," said Discovery in a statement.
Original Productions, which produced Deadliest Catch, mourned his passing.
"The entire Original Productions Family is heartbroken with this news. Our thoughts and prayers are for the McMahon Family," read a statement from the company's CEO, Philip D Segal.