Jimmie Johnson will not race this weekend in NASCAR’s Cup Series street race in Chicago following the deaths of his wife’s parents and a nephew in Oklahoma.

The bodies of Jack Janway, 69; his wife, Terry Janway, 68; and their grandson Dalton Janway, 11, were discovered Monday at a home in Muskogee, Oklahoma, located about 50 miles southeast of Tulsa, Muskogee police spokesperson Lynn Hamlin said. Hamlin said investigators believe Terry Janway shot and killed her husband and grandson before shooting herself.

Police responded to the home after a woman called 911 to report a disturbance with a gun before hanging up, Hamlin said.

When police arrived on the scene, they found one person near the front door of the home and then heard a gunshot from further inside, where officers later found two other people dead, Hamlin said. Hamlin confirmed the three are the parents and nephew of Johnson’s wife, Chandra Janway.

NASCAR this week is preparing for its first foray into street course racing. Johnson, a seven-time Cup Series champion, is racing on a part-time basis this year as co-owner of Legacy Motor Club. He drives the No. 84 Carvana Chevrolet.

“The Johnson family has asked for privacy at this time and no further statements will be made,” Legacy Motor Club said in a tweet.

“We are saddened by the tragic deaths of members of Chandra Johnson’s family,” NASCAR said in a statement. “The entire NASCAR family extends its deepest support and condolences during this difficult time to Chandra, Jimmie and the entire Johnson & Janway families.”

The Associated Press contributed to this report.