The Los Angeles Police Department and LA County Department of Children and Family Services are both investigating after someone anonymously reported the incident last Wednesday on the tarmac, a source told People magazine.
Pitt is accused of getting verbally abusive with one couple's kids, as well as getting "physical," the source said. Jolie was present at the time, along with at least some of their other children.
Another source said that Pitt, 52, did not return to the LA family home with Jolie, 41, and the children after the incident.
TMZ first reported news of the child services investigation.
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A source close to Pitt said that that he is not taking the investigation lightly.
"He takes the matter very seriously and says he did not commit any abuse of his children," the insider said. "It's unfortunate that people involved are continuing to present him in the worst possible light."
Jolie, 41, filed for divorce and requested sole physical custody of the couple's six children - Maddox, Pax, Zahara, Shiloh, and twins Knox and Vivienne. In documents filed in court on Monday, Jolie cited irreconcilable differences in ending their marriage of two years.