Motorists driving towards Reading and London through Swindon are still facing delays.
The M4 has been closed for a number of hours after police closed the road eastbound between Junction 16 and Junction 15.
LIVE UPDATES: M4 remains closed as police launch investigation
It is currently unknown when the motorway will reopen, or what has caused the cops to close it for so long.
In the early hours of Saturday morning, Wiltshire Police announced the motorway would be closed for the foreseeable future.
Traffic was closed in both directions but at 9:30 am the westbound stretch of the motorway reopened.
Other roads in Swindon were closed, with Croft Road in Wroughton being cordoned off.
As the morning went on traffic started to build up with the traffic backing up on the A419 southbound towards the Badbury Roundabout as far as the turning for Highworth.
There are also delays around the Mannigton roundabout and the Transfer Bridges roundabout, which is on the diversion route.
There are 45 mins delays on the #M4 eastbound carriageway between J17 and J16 on the approach to the closure at J16. The eastbound carriageway remains closed whilst @wiltshirepolice continue their investigation. pic.twitter.com/nv3WHlFmRL
— National Highways: South-West (@HighwaysSWEST) October 1, 2022
At present, there are delays of up to 45 minutes on the M4 eastbound on the approach to Junction 16 of the motorway.
Police are still conducting an investigation into the incident.
Wiltshire Police have been approached for comment.