STS-95 crewmember, astronaut and US Senator John Glenn poses for his official NASA photo taken April 14, 1998. [Photo/Agencies]

US space agency NASA said Glenn died Thursday at the Ohio State University Wexner Medical Center in Columbus.

"We are saddened by the loss of Sen. John Glenn, the first American to orbit Earth," NASA tweeted.

"A true American hero. Godspeed, John Glenn. Ad astra."

Glenn, born in Ohio in 1921, became the first American to orbit the Earth and the fifth person in space in 1962.

"His flight on Friendship 7 on Feb. 20, 1962, showed the world that America was a serious contender in the space race with the Soviet Union," NASA said in a profile. "It also made Glenn an instant hero."

After Glenn left NASA, he served four terms as a U.S. senator from the state of Ohio.

In 1998, 77-year-old Glenn got to fly to space again. He flew with six other astronauts on the space shuttle Discovery to become the oldest person to fly in space.