Isaiah Thomas' sister killed in car accident

The 22-year-old sister of Boston Celtics star Isaiah Thomas died in a car accident Saturday morning in Federal Way, Washington, family friends told the Tacoma News Tribune.

The Celtics issued this statement on Twitter:

https://twitter.com/celtics/status/853398633613492225

According to the News Tribune, 22-year-old Chyna Thomas died at the scene of an accident on the shoulder of the I-5 at around 5 a.m. Saturday morning.

A Washington State Patrol spokesman said the car was being driven normally at first, and then "all of a sudden it started to drift very casually onto the left shoulder" and then hit a barrier, which "vaulted the vehicle head-on into the sign post." Chyna Thomas was reportedly not wearing her seat belt.

"The NBA family mourns the tragic passing of Chyna Thomas and we send our deepest condolences to Isaiah, his family and the Celtics organization during this difficult time," NBA commissioner Adam Silver said in a statement.

Isaiah Thomas and the Celtics open their playoff series against the Chicago Bulls on Sunday in Boston.