Brad Pitt is "extremely" worried about his estranged son Pax Jolie-Pitt following his serious electric bike accident.

Pitt and Angelina Jolie's 20-year-old son landed in the intensive care unit with head injuries and hip pain after he allegedly crashed his bike into the back of a car in Los Angeles on July 29.

The collision knocked Pax -- who had no helmet on -- out cold, with eyewitnesses at the scene even initially thinking he had died in the crash.

While Pax has since been released from the ICU, his estranged dad remains "extremely concerned" about his condition, unnamed sources "close to" Pitt recently told the outlet.

Shiloh Jolie-Pitt, Pax Thien Jolie-Pitt and actress Angelina Jolie
(L-R) Shiloh Jolie-Pitt, Pax Thien Jolie-Pitt and actress Angelina Jolie attend the Los Angeles premiere of MSNBC Films' "Paper & Glue: A JR Project" at Museum Of Tolerance on November 18, 2021 in Los Angeles, California. JC Olivera/Getty Images

The "Bullet Train" star was reportedly "shocked and emotional" when he was informed about Pax's bike accident.

According to TMZ's insiders, Pitt has found it "alarming" that Pax rarely wears a helmet when riding his e-bike despite allegedly having been involved in multiple accidents over the past several months.

Pitt is reportedly "grateful" that he's been able to get updates about Pax's accident and condition from "concerned people around the family" as he doesn't have direct contact with his son, the sources added.

Brad Pitt
Brad Pitt (C), (L-R) Pax Thien Jolie-Pitt, Shiloh Nouvel Jolie-Pitt,, Maddox Jolie-Pitt, Jane Pitt, and William Pitt arrive at the Premiere Of Universal Studios' "Unbroken" at TCL Chinese Theatre on December 15, 2014 in Hollywood, California. Frazer Harrison/Getty Images

Earlier this week, a family friend, who was not identified, told E! News that Pax was no longer in intensive care but still has a "long road" ahead in terms of recovery.

"He suffered complex trauma, and now begins the long road of recovery and physical therapy," the source said.

"Pax and Angelina are deeply grateful for the quick and life-saving action of first responders, and the outstanding medical care he received," the insider added.

In addition to Pax, Pitt and Jolie have five other children: Maddox, 22, Zahara, 19, Shiloh, 18, and twins Vivienne and Knox, 15.

Angelina Jolie and kids
 Angelina Jolie with children Knox Leon Jolie-Pitt, Vivienne Marcheline Jolie-Pitt, Pax Thien Jolie-Pitt, Shiloh Nouvel Jolie-Pitt, Zahara Marley Jolie-Pitt and Maddox Chivan Jolie-Pitt attend "The Boy Who Harnessed The Wind" Special Screening at Crosby Street Hotel on February 25, 2019 in New York City. Monica Schipper/Getty Images for Netflix

However, their children have distanced themselves from their father in the years after Jolie filed for divorce from Pitt and accused him of assaulting and verbally assaulting her and two of their kids during a 2016 flight. The actor denied the allegations and was never charged.

Shiloh filed a petition in May to have her dad's last name officially removed from her surname. Zahara and Vivienne have also publicly denounced the Pitt name in recent months.

In 2020, Pax allegedly slammed Pitt as a "world-class a*shole" in an Instagram post shared on Father's Day.

"Sadly, their rift has only widened over time," an unnamed source told Us Weekly in a report published in June. "The boys found it difficult to reconcile with Brad despite his repeated apologies and efforts to rebuild trust."

A second anonymous source told the outlet, "Brad's relationship with Maddox and Pax is nonexistent at this point, and he barely, if ever, hears from Zahara."

Angelina Jolie, Maddox and Pax
Maddox Jolie-Pitt, Angelina Jolie and Pax Jolie-Pitt attend the "First They Killed My Father" premiere during the 2017 Toronto International Film Festival at Princess of Wales Theatre on September 11, 2017 in Toronto, Canada. Alberto E. Rodriguez/Getty Images
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Brad Pitt, Angelina Jolie