Police received a report of a road traffic collision on the A4042 in Cwmbran at around 12.25pm on Thursday 12 February.
Officers attended alongside the Welsh Ambulance Service regarding a collision that involved three cars and a pedestrian.
The pedestrian, a 17-year-old teenage girl from Caldicot, was sadly pronounced dead at the scene; her family have been informed.
The road between the Crown and Turnpike roundabouts is partially closed, with one lane heading north currently open.
The southbound section remains closed at this time and diversions are in place.
Anyone with relevant information, including CCTV or dashcam footage, is asked to contact Police via the website, call 101 or DM on the Gwent Police Facebook or X social media pages, quoting log reference 2600046163.