Jimmie Johnsons in-laws and nephew found dead in their home

THEIR DEATHS ARE BEING INVESTIGATED AS A MURDER-SECOND-DEGREE. JIMMY JOHNSON'S MOTHER-IN-LAW IS THE PRIMARY SUSPECT. THIS IS THE OKLAHOMA HOME. THE IN-LAWS OF SEVEN-TIME NASCAR CUP CHAMP JIMMY JOHNSON AND THE LOCATION OF A HEART-BREAKING MURDER- MURDER-SUICIDE INVOLVING THE COUPLE. >> IT IS ONE OF THOSE CULTURAL COMMUNITY SHOCKS. >> Reporter: EARLY MONDAY NIGHT, THE POLICE DEPARTMENT SAYS THEY RECEIVED A 911 CALL FROM A WOMAN SAYING THERE WAS

A DISTURBANCE AT A RESIDENCE INVOLVING A GUN BEFORE SHE ABRUPTLY HUNG UP. WHEN THE OFFICERS ARRIVED, THEY FOUND ONE PERSON DEAD IN THE FRONT HALLWAY. THAT'S WHEN THEY SAY A SINGLE SHOT WAS FIRED FROM INSIDE THE HOME. POLICE EVENTUALLY FOUND TWO MORE BODIES, LATER IDENTIFYING THE VICTIM AS 69-YEAR-OLD JACK, HIS WIFE AND THEIR SON. POLICE BELIEVE TERRY MADE THE INITIAL 911 AND THEN SHOT AND KILLED

HER HUSBAND AND GRANDSON BEFORE TAKING HER OWN LIFE. >> IT WAS TRAUMATIZING TO FIND OUT THAT A LONG-STANDING FAMILY WHO HAD MADE SO MANY CONTRIBUTIONS TO OUR FAMILY WERE INVOLVED IN THIS TYPE OF INCIDENT. IT WAS MORE BONE-CHILLING WHEN WE FOUND OUT THERE WERE CHILDREN INVOLVED. >> Reporter: ROCKING THE COMMUNITY, AS WELL AS THE NASCAR RACING WORLD. TERRY AND JACK WERE THE PARENTS OF JIMMY JOHNSON'S

WIFE. JOHNSON HAS APPEARED MULTIPLE TIMES ON "TODAY." LAST YEAR HE ANNOUNCED HE WAS TAKING A STEP BACK FROM FULL-TIME RACING TO SPEND MORE TIME WITH HIS FAMILY. >> HONESTLY, THE EXPERIENCE I'VE HAD IN THE LAST FEW YEARS HAS BEEN FULFILLING. I'VE HAD THE EXPERIENCE I WANTED TO HAVE. >> Reporter: THIS IS NOT THE FIRST TIME HIS WIFE'S FAMILY HAS EXPERIENCED A TERRIBLE LOSS. HER BROTHER JORDAN

WAS KILLED IN A 2014 SKY DIVING INCIDENCE. SCHOOLS REMEMBERING THE YOUNGEST VICTIM SAYING THE FIFTH GRADER WAS CHERISHED BY HIS TEACHERS AND CLASSMATES. AUTHORITIES HAVE NOT REVEALED A POTENTIAL MOTIVE IN THE CASE. A MEMBER OF THE FAMILY WROTE ON FACEBOOK, PLEASE TELL ME THIS ISN'T REALLY HAPPENING. PLEASE GOD, SOMEONE. FOR THEIR PART, THE JOHNSON FAMILY IS ASKING FOR PRIVACY. JIMMY JOHNSON WAS SCHEDULED TO COMPETE IN