A 50 year old man from Newport has been arrested on suspicion of causing serious injury by dangerous driving.
Gwent police have also confirmed that two men have been admitted to hospital, both having sustained life changing injuries.
The A40 dual carriageway was closed this morning (November 6th) in both directions, near to the Gibraltar tunnels.
At 5.50am this morning (Friday 6th November 2015) Gwent Police received reports regarding a two vehicle road traffic collision, southbound on the A40 in Monmouth.
Following this incident, the police were notified of another two vehicle collision in the same location on the northbound carriageway. During this incident, two people sustained minor injuries.
The dual carriageway has been re-opened, and a spokesperson for Gwent police told the Ross Gazette: "Traffic is now flowing in both directions."