Jimmie Johnson's racing team has withdrawn from this week's NASCAR Cup Series race in Chicago after the tragic deaths of his in-laws in Oklahoma on Monday.
Muskogee Police are investigating it as a murder-suicide, they told TMZ.
His 11-year-old nephew also was shot and killed.
"The Johnson family has asked for privacy at this time and no further statements will be made," Legacy Motor Club said in a statement.
Jack and Terry Janway, the parents of Johnson's wife, Chandra Janway, were found dead along with Dalton Janway, the couple's grandson. Muskogee Police told TMZ that Chandra's mother, Terry, is considered the suspect.
Johnson and Chandra Janway have been married since 2004. They have two daughters.
Johnson is a seven-time NASCAR Cup Series champion.
He returned to NASCAR in 2023 as an owner and part-time driver. Chicago would have been just his fourth race driving this season.