Dale Cregan's police van in collision on the way to court

The 29-year-old murdered PCs Fiona Bone and Nicola Hughes after luring them to a house in September

Dale Cregan has admitted killing four people, including two unarmed police officers (PA)

The police van carrying quadruple killer Dale Cregan was reportedly involved in a collision en route to court today.

The van was travelling to Preston Crown Court, where Cregan has been on trial, according to the Press Association.

Four prison officers suffered minor injuries and have been taken to hospital for treatment, while one prisoner was injured, Greater Manchester Police said.

On Wednesday Cregan dramatically changed his plea on the 54th day of the a murder trial at Preston Crown Court, and admitted shooting dead Mark Short, 23, in a pub and then murdering his father, David Short, 46. He remains on trial as he continues to deny one remaining count of attempted murder.

His defence barrister said he would now die in prison.

The 29-year-old murdered PCs Fiona Bone and Nicola Hughes after luring them to a house in Mottram, Greater Manchester in September last year.

A police statement said: “Shortly before 9.40am on Friday 24 May 2013, a road traffic collision occurred by the roundabout at the exit of junction 31A of the M6 northbound.

“The collision involved two prison vans on the way to Preston Crown Court as part of a high profile trial.”

Sources said the crash was simply a collision between two prison vans.

It is understood prison vans in convoy have to travel close together so no vehicles can come between them.

His co-defendants deny all the charges against them, and the trial continues.