St John intensive care paramedic Steve Brake said an ambulance arrived at 9.40am followed by a second just before 10am.
Defibrillators were used to try to revive Dr Ridings and Mr Brake "worked on him" for 40 minutes before he was declared dead.
Dr Keith Ridings
Ana Vuletic, whose family owns Baker Boy, said Dr Ridings had been coming to the cafe for the past 15 years.
"He always ordered a long black coffee ... He used to come every day but recently he came once a week. His wife had been very unwell."
His daughter Penny Ridings said she spoke to her father on Tuesday when he told her he felt he and his wife June had lived a happy and full life.
Dr Ridings worked as a health management consultant and locum in Rotorua until March this year. He was medical superintendent-in-chief of Bay of Plenty Hospital Board in Whakatane from 1986 to 1989 and Rotorua Hospital medical superintendent from 1977 to 1979.
He worked as the director-general of health in Samoa from 1979 to 1982 and had also worked for the New Zealand Department of Health.
Dr Ridings' friend Dr Bryan Jew was shocked to hear the news but said he would remember him as a respected medical professional and a talented pianist.
"Keith was Rotorua," Dr Jew said. "He was born and raised here, he had his medical practice here. He came and went over the years but he always came back."
Dr Jew, 86, and Dr Ridings, met in 1960 when they were general practitioners in their respective private practices.
"My fondest memory will be Keith playing the piano.
"He was quite talented and used to play at what was Brent's Hotel to help pay for his medical studies."
Dr Jew said he had spoken to Dr Ridings four days before he died to check on his wife's health and he last saw him in early December.
"It was my wife, Erica, and my 60th wedding anniversary and Keith came to the party.
"It was the last time I saw him and the last time I heard him play the piano."
He said Dr Ridings had a grand piano at his home which he played regularly.
They both attended Otago's School of Medicine before Dr Ridings returned to Rotorua as a general practitioner and started a private practice around 1960.
Mr Ridings' funeral will be at St Luke's Anglican Church on Tuesday at 1pm and will be followed by a private service for family and close friends at the Rotorua Crematorium Chapel.
