MUSKOGEE, Okla. (AP) — Police in Muskogee, Oklahoma, confirmed Tuesday they are investigating the shooting deaths of three relatives of seven-time NASCAR champion Jimmie Johnson.

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, 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.

Johnson’s race team, Legacy Motor Club, announced on Twitter it was withdrawing his No. 84 Carvana Chevrolet from this weekend’s NASCAR Cup Series event in Chicago. The team added: “The Johnson family has asked for privacy at this time and no further statements will be made.”

“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.”