A school bus driver has been placed on leave as a “cautionary matter” pending the outcome of an internal review after allegations surfaced that a 6-year-old student repeatedly sexually assaulted other students on the bus, school officials confirmed Wednesday.

Boston Renaissance Charter Public School officials learned of the assaults on Nov. 3 and reported the incidents to Boston police and child welfare advocates that day. The allegations became public earlier this week after a Facebook post by a friend of the victim’s mother was shared thousands of times.

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The mother said she wondered how the bus driver did not notice what was happening during any of the alleged 10 assaults, the Boston Globe reported. Her son, who is developmentally delayed and suffers from attention-deficit hyperactivity disorder, reportedly sits at the front of the bus across from the driver.

The students attend Boston Renaissance Charter Public School, which is not part of the Boston Public Schools department, but buses are operated by the district, BPS spokesman Daniel O’Brien said.

All BPS bus drivers are employed by TransDev, a third-party operator.

O’Brien said in a news release earlier this week that Boston Public Schools were never notified of the alleged incidents and only learned of them during the social media firestorm.

O’Brien did not identify the driver and could not offer a timeline for the review.