NASCAR is rallying around Jimmie Johnson amid an unimaginable family tragedy.

The organization offered a message of support to the race car driver and his family following the loss of his mother-in-law Terry Janway, 68, father-in-law Jack Janway, 69, and 11-year-old nephew Dalton in an apparent murder-suicide in Oklahoma on June 26, police confirmed to E! News.

"We are saddened by the tragic deaths of members of Chandra Johnson's family," NASCAR said in a statement to E! News on June 27. "The entire NASCAR family extends its deepest support and condolences during this difficult time to Chandra, Jimmie and the entire Johnson & Janway families."

Terry, the mother of Jimmie's wife Chandra, is believed to be the primary suspect in the killings, authorities confirmed.

E! News has reached out to reps for Jimmie and have yet to hear back. No further details have been shared publicly at this time.

Muskogee Police Department chief of police Johnny Teehee said in a press release that on June 26 at approximately 9:05 p.m. officials received a call from a woman who stated "that there was a disturbance and someone had a gun and then hung up."

"When officers arrived on scene they saw a subject laying in the hallway inside the front door," he continued. "Shortly after arriving officers heard another gunshot from further inside the house. Officers conducted a rescue of the subject laying inside the hallway and determined the subject was deceased."

Police then proceeded to make announcements for other occupants inside the residence to come outside.

"Once enough officers arrived on scene," Teehee said, "a search of the residence was conducted and two more subjects were found deceased inside the residence."

In the wake of the deaths, Muskogee mayor Marlon Coleman called the incident "even more bone-chilling" to know there was a child involved.

"It was traumatizing to find out that a long-standing family who had made so many contributions to our community were involved in this type of incident," he told Fox23. "I knew Dr. Janway. Dr Janway has worked on me, we've been acquaintances for a very, very long time since I've been in Muskogee. Just knowing that it was him and his family took a different toll on me."