8:31 AM PT -- 2/20 The parents of Baxter's estranged wife say the rugby player was in a "downward spiral" prior to the murder-suicide ... claiming it all started when Hannah left Baxter after 11 years of marriage.
The parents detail Hannah's relationship with Baxter, saying he was controlling and abusive ... and believe he hacked Hannah's phone so he could track her every move.
The parents question how Baxter was able to get so close to Hannah during the attack ... explaining he wasn't allowed within 65 feet of her following a recent assault, and there's no way she would have allowed him to come close.
A former pro-Australian rugby player murdered his wife and 3 young children in an apparent murder-suicide ... according to law enforcement officials in Australia.
42-year-old Rowan Baxter -- who played for the New Zealand Warriors in the National Rugby League (NRL) -- was found in his car early Wednesday morning along with his wife, 2 young daughters and his son. The kids were aged 6, 4 and 3.
Officials believe Baxter doused the car with gasoline and set it on fire. Witnesses say they saw Baxter's wife trying to escape the car while yelling, "He's poured petrol on me."
Devastating news out of Camp Hill. My heart goes out to the families and community going through this tragic time and the emergency responders confronting what would be a shattering scene. If you or anyone you know needs support, call Lifeline on 13 11 14. https://t.co/qJDieLMRiN
Emergency responders raced to the scene -- and Baxter's wife was transported to a nearby hospital ... but she ultimately succumbed to her injuries. Emergency responders also reportedly tried to revive Rowan, but he was declared dead.
Police say Rowan's wife had been driving the car and he was sitting in the front passenger seat.
A Good Samaritan who tried to help the family was also hospitalized with facial burns, according to local media.
Scott Morrison -- the Prime Minister of Australia -- has issued a statement about the situation saying, "My heart goes out to the families and community going through this tragic time and the emergency responders confronting what would be a shattering scene."
Rowan and his wife had been running a fitness company called Integr8 in Brisbane. They reportedly separated late last year and were trying to hammer out custody arrangements.
Baxter stayed around the game after his playing career was over, working as a fitness coach for teams in NRL, Super Rugby and the Australian Football League.