Cricket South Africa announced 73-year-old Koertzen's death but gave no details of the incident other than to say the renowned umpire died following a car accident.
South African Koertzen stood in 108 Tests, a record 209 one-day internationals and 14 Twenty20 internationals over an 18-year career.
His Test debut was in South Africa's first home series back in international cricket in 1992 after the country's 22-year ban because of apartheid. He retired in 2010.
Koertzen was famous for his unique method of giving a batter out, where he'd slowly raise his left arm with his finger pointing at the batter to signal the dismissal. It became known as the "slow finger of death." He was one of cricket's most respected umpires.
"The passing of this titan is a sad loss for the game," said Cricket South Africa chief executive Pholetsi Moseki, who paid tribute to Koertzen's "selfless dedication and commitment."
Ponting said in a social media post that he was "extremely saddened" by news of Koertzen's death.
"My deepest sympathy goes out to his family and friends," Ponting said on Twitter. "He was a great umpire and a better person. I always enjoyed sharing the field with him."
South Africa's Algoa FM radio station reported that Koertzen and three other people were killed in a head-on collision near the town of Riversdale in the Western Cape province. Koertzen was returning to his home in the Eastern Cape province after playing in a golf tournament when the crash happened, the station reported.
12°C