Randolph Mantooth, best known for his role as Johnny Gage on the 1970s NBC drama "Emergency!," died Thursday at a hospice facility in Ventura, Calif. He was 80. His brother, Donald Mantooth, told The Hollywood Reporter that the actor had been ill for several years.

Mantooth rose to prominence in 1972 with "Emergency!," a series credited with introducing the profession of paramedics to a wide audience. He starred alongside Kevin Tighe and performed many of his own stunts on the show, which ran for six seasons. He also reprised his role as Gage in appearances on "Adam-12."

He was an advocate for firefighters, paramedics, and EMTs, and often spoke about the cast's desire to portray these professionals accurately. "We wanted to make them look like exactly who they were — heroes," Mantooth said in a 2013 interview, as reported by the Television Academy. He added, "Now, everyone’s got to have a flaw. It drives me crazy. I don’t care about your flaws. Just show me what you do. How’s the job done? And do it real. Show me!"

Born in Sacramento, Calif., Mantooth developed an interest in acting through school plays. After attending Santa Barbara City College, he received a scholarship to the American Academy of Dramatic Arts in New York. He signed with Universal after being noticed in a stage production of "Philadelphia, Here I Come."

Before "Emergency!," Mantooth appeared in numerous television series, including "Ironside," "The Virginian," "Marcus Welby, M.D.," and "Alias Smith and Jones." Following the conclusion of "Emergency!," he continued his acting career in shows such as "Dallas," "Charlie’s Angels," "Criminal Minds," and "Sons of Anarchy." He also maintained a long presence in daytime television, with roles on "Loving," "General Hospital," and "As the World Turns."

Mantooth's "Loving" co-star Rena Sofer remembered him as a mentor and a "dear friend." "This man came into my life when I was 18 years old and never left. He took me under his wing as he did to most young actors he ever met," Sofer posted on Instagram. "He treated me with respect and kindness but most of all friendship."

Mantooth is survived by his wife, Kristen, and his siblings, Donald and Tonya.