The M4 between Junctions 17 and 18 in both directions remains closed following two fatal road traffic collisions earlier this morning.
The first collision occurred shortly after 1.30am this morning involving one car on the eastbound carriageway.
One man was pronounced dead at the scene, while another man suffered life-threatening head injuries and was taken to Southmead Hospital in Bristol.
Two hours later there was another collision on the M4 between junction 17 and 18, westbound involving two articulated lorries, a car and a van.
One man was pronounced dead at the scene, while two men were taken to Southmead Hospital.
One of the vehicles was carrying propane gas canisters which were leaking, and the fire service were called to make safe.
Supt Phil Staynings said: “We had to respond to two truly tragic incidents this morning and our thoughts are with the family and friends of the victims.
“This is a complex incident that put huge pressure on all of the emergency services this morning and will continue to take a considerable amount of time to investigate thoroughly.
“We appreciate the public’s patience on this regarding the closure of the M4 and we are working closely with Highways England to ensure we can have the road back open when it is appropriate to do so.
“I would like to take this chance to appeal to anyone who may have witnessed this incident or may have been driving along this stretch of M4 at the same time and could have dash cam footage that could prove helpful to our investigations to please contact us on 101.”
We are hoping to have the eastbound carriageway of the M4 re-open by midday but the westbound carriageway is likely to remain closed for the remainder of the day.
We would encourage people to avoid the area if possible due to increased volumes of traffic on the surrounding roads and for full details of the diversion currently in place, please visit Highways England here.
Anyone who witnessed the collision is asked to contact Wiltshire Police on 101 or Crimestoppers on 0800 555 111 where information can be left anonymously.