President Jimmy Carter was hospitalized in Cleveland after an unknown health issue on a plane, CNN reported Tuesday.

Carter, 85, was transferred to Metro Health Hospital in Cleveland at 11:30 a.m. after paramedics met Carter’s plane upon its arrival, an airport spokeswoman told CNN.

The 39th president was scheduled to be at a Lyndhurst bookstore Tuesday afternoon to sign copies of his recent book, “White House Diary.”