The journalist was killed in a car crash Friday morning on New York's Long Island. His car collided with a propane tanker and he was pronounced dead at Southampton Hospital. Threlkeld was 74 years old.
The driver of the tanker, Earl Fryberger Jr., of Coatesville, Penn., was not injured, said police, who are investigating the accident.
Threlkeld worked for both CBS and ABC News before retiring in 1998.
During his long career, he covered the Persian Gulf War and the Vietnam War, as well as the Patty Hearst kidnapping and the assassination of Robert F. Kennedy. He also won several Emmys and Overseas Press Club awards.
On Friday, ABC News president Ben Sherwood called Threlkeld a "terrific writer and master storyteller... always full of ideas."
He is survived by his wife, Betsy Aaron, a former CBS and CNN correspondent; a brother, Robert, of Port Townsend, Wash.; two children, Susan Paulukonis, of Alameda, Calif., and Julie Threlkeld of Yonkers, N.Y.; and two grandchildren.
The Associated Press contributed to this report.