Jackson Kids Involved in Car Accident

UPDATE 6:00 PM PT: Sources close to the Jackson family tell us Grace Rwaramba -- the kids' nanny -- was driving the car with the kids inside. We're told the Jackson caravan was on the way to karate class, but the paparazzi gave chase ... and that's when one papper allegedly smashed into the back of the Jackson Escalade that wasn't carrying the kids.

UPDATE 5:45 PM PT: Law enforcement sources tell TMZ the car that was hit was a Jackson security car, which was following the car carrying the Jackson kids. The kids were NOT in the car that was struck by the paparazzo.

Cops also tell us a hit-and-run report was taken on the scene around 2:20 PM near the crash site in Sherman Oaks -- just a few miles from the Jackson home in Encino. It is currently under investigation.

UPDATE 5:30 PM PT: Witnesses tell TMZ the driver who struck the Jackson car fled the scene after impact. In California, leaving the scene of an accident without exchanging information is a crime. The D.A. could file a felony hit-and-run charge if the evidence is there.