NAIROBI, Kenya -- Daniel Rudisha, an Olympic silver-medalist runner in 1968 and the father of two-time Olympic 800-meter champion David Rudisha, has died. He was 73.

David Rudisha made the announcement on Thursday, saying his father had a heart attack on Wednesday while undergoing dialysis treatment. The elder Rudisha had struggled with diabetes for many years and had been in the intensive care unit this week.

"Our beloved father sadly left us last night," David Rudisha said. "He had recovered and was on his way to fine health having been taken off the intensive care unit. He was speaking well and joking as usual while undergoing his dialysis treatment but at around 11 p.m. he suffered a sudden heart attack.

"We will try to remain strong during these difficult times."

Daniel Rudisha won silver in the 4x400-meter relay at the 1968 Mexico City Olympics, one of Kenya's earliest successes in track. Kip Keino broke onto the scene to win gold for Kenya in the 1,500 meters at the same Olympics.

David Rudisha, a world record-holder and two-time world champion in the 800, often referred to his father as his inspiration. He gave his dad his first gold medal from the 2012 London Olympics, when he set the current world record. David posted pictures of himself and his father on Twitter this week.

Me and my ailing father,,,, wish him quick recovery. Long live my dad. pic.twitter.com/wR8qeWlbzR — David Rudisha (@rudishadavid) March 5, 2019

The Kenyan track federation said Daniel Rudisha was a "pioneer" for Kenyan athletics.

"(He) set the foundation for the current crop of athletes," Athletics Kenya said.