An 85-year-old Oakton woman died during a police transport early Tuesday morning, Fairfax County police said.

Mary Jean Martin, of the 11100 block of Stuart Mill Road, suffered medical distress while in a police cruiser on the way to Woodburn Mental Hospital in Annandale for a mental evaluation, police said.

Martin’s family members had called police to Inova Fairfax Hospital around 3:30 a.m. after family members became concerned for her safety because she was acting irrationally and was confused, said Officer Bud Walker, a Fairfax County police spokesman.

Officers placed Martin in the cruiser without incident and began driving her to the mental hospital, which is only a short distance from Inova, Walker said. Martin was not handcuffed during the trip, Walker said.

After Martin went into distress, officers immediately summoned rescue personnel and began performing CPR on the woman, Walker said. She was then transported back to Fairfax Hospital, where she was pronounced dead, police said.

The Virginia medical examiner will determine the cause of the woman’s death and the investigation remains ongoing.