Petara Cordero was in Smith's 2019 Lamborghini when the couple pulled over to the side of I-90 West in Cleveland around 2 a.m. after a tire blew. The car veered left and hit the median.
Without significant injuries, Cordero got out of the car. Shortly after, a woman in a 2017 Mazda 3 hit the passenger's side of Smith's car and Cordero, who was standing on the shoulder, Cleveland police said in a statement to CNN.
Police and paramedics arrived on scene shortly after. Cordero, 26, was taken to the hospital, where she was pronounced dead.
The driver of the second car was also taken to the hospital, where she was to be released after receiving care. The woman admitted she had been drinking, police said. A toxicology report is pending.
Smith was not impaired, police said.
The incident is under investigation, and no charges have been filed as of this time.
The Browns said players were notified during a team meeting. Head coach Freddie Kitchens also visited Smith at his home.
"Words cannot describe the sorrow we feel for Chris following the loss of his girlfriend, Petara," team owners Dee and Jimmy Haslam said in a statement. "Our entire organization mourns with Chris, his family and the Cordero family. We will do everything possible to offer them our support, comfort and any resources in this most difficult time."
The Browns will have counselors on site throughout the week to provide emotional support for players and staff.
Mary Cay Cabot of Cleveland.com says Cordero and Smith's daughter, Haven Harris Smith, was born four weeks ago. Smith was excused from the Browns' preseason game against the Indianapolis Colts in August, so he could attend the birth of his daughter.
Smith, 27, was drafted in 2014 by the Jaguars. He has been with the Browns since last year.