The A5 remains closed between Towcester and Weedon heading into rush hour on Tuesday morning (May 10) following a crash in the early hours.
A spokesperson for the agency confirmed Northamptonshire Police are at the scene and managing the incident.
Traffic is being diverted via the A43, A45 and M1.
Latest estimates say the road is unlikely to reopen until mid-morning and drivers are being advised to re-plan journeys.
UPDATE: Police later confirmed a 19-year-old van driver died and a lorry driver was seriously injured in the crash.