Emergency services have been seen attending a crash on City Road in Reading.
Traffic is backed up from the roundabout with Park Lane to the roundabout with Hildens Drive.
Members of the public spotted police and an ambulance on the scene.
It is recommended to avoid the area.
Saint Paul's Catholic School, which is within the police cordon, has said: "All children have arrived at school okay."
Parents were notified of the accident via parent mail this morning with advice as to where best to drop off on the school run.
A spokesperson for the school added: "We do not know how long the cordon will be in place."
If the cordon is still in place by the end of the school day parents will be given further guidance.
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