The southbound Cherry Avenue off-ramp of the 405 Freeway was shut down after a fatal medical emergency in a car Tuesday afternoon, according to authorities.

There was no collision, but an elderly woman in a car on the freeway suffered an unspecified medical emergency and died on the scene, according to California Highway Patrol Sgt. Larry Markey. The coroner’s office determined the woman died of natural causes.

The woman’s granddaughter-in-law, Elena Anderson, said in an email that the woman’s granddaughter, who was in the passenger seat, “was able to get the car to safety, heroically, as her grandma passed away in the driver seat.”

CHP issued a SIG alert for the area, anticipating the off-ramp to be closed until approximately 3 p.m., to allow for family members to be notified and a pickup by a mortuary to be arranged.

Editor’s note: This story was updated Thursday, March 18, with information from Elena Anderson.