A woman has been killed and two others badly injured in a crash on the M4 motorway today.
The victim, who is aged in her 60s, was a passenger in a black Nissan car which was involved in a crash with a white van in the outside lane near Reading, Berkshire, at about 8.45am this morning.
Thames Valley Police confirmed the death and said two other people were "seriously injured" and have been taken to hospital where they remain in a "serious condition".
National Highways had earlier reported that some vehicles had become trapped in the queues. A diversion route has been put in place, BerkshireLive reports.
Investigating officer Detective Constable Mark Dunne, of the serious collision investigation unit, said: "Tragically, as a result of a serious collision this morning, a woman has died and two others have been seriously injured.
"The woman's next of kin have been made aware and are being offered support by specially trained officers, and my thoughts and the thoughts of Thames Valley Police remain with them at this extremely difficult time."
Both carriageways between junction 11 at Reading and junction 12 were closed as motorists were warned to expect delays of at least 45 minutes.
Lanes one to three on the eastbound carriageway have reopened., but police have previously warned that the westbound carriageway is likely to remain shut for "much of the day".
National Highways said in an update this afternoon: "Thames Valley Police, National Highways Traffic Officers and service providers are on scene.
"Initially, the eastbound carriageway was closed however lanes 1 and 2 (of 4) are now open to traffic. Police collision investigation work will be undertaken, therefore the closure is expected to be in place for several hours this afternoon."
Thames Valley Police added that is now appealing for witnesses to the crash to come forward.
"I am appealing to anybody who was driving on the M4 this morning at around the time of the collision to please contact 101, quoting incident reference 320 (7/3) if you witnessed what happened," added DC Dunne.
"I would also like to hear from anybody who may have dash-cam footage to please check this, and if it has captured the collision, or the moments leading up to the collision, to please get in touch with us."