Anti-terrorism officers have joined the murder investigation into Jo Cox’s death.
Officers from the North East Counter Terrorism unit are working with West Yorkshire Police to probe the death of the MP in Birstall.
Meanwhile a charity fund set up by friends of Mrs Cox has met with a staggering response.
In less than four hours, more than £50,000 has been donated to help three charities in memory of the murdered MP.
Police are still holding a 52-year-old man in connection with her death in Birstall.
The man, named locally as Tommy Mair, of Batley, was arrested within minutes of the attack.
Temporary Chief Constable Dee Collins said: “We have now confirmed that just before 1pm on Thursday Jo arrived in a vehicle in company with two colleagues outside the Library on Market Street and whilst enroute to the library where she had a scheduled constituency meeting, she was attacked and sustained serious injuries from both a firearm and a knife.
“Despite assistance from passers-by, the ambulance service and police officers who were quickly on the scene, she sadly died of her injuries.
Read more: Jo Cox MP dies after attack in Birstall
“During the course of the incident a 77-year-old man bravely intervened to assist Jo and in doing so sustained a serious injury to his abdomen and although now stable he remains in hospital.
“We have had overwhelming support from the public in respect of this incident which assisted us in quickly locating a suspect who was tackled by unarmed officers and arrested.
“A murder investigation is under way by West Yorkshire Police who are working together with the North East Counter Terrorism Unit, who will bring specialist assets in support of the enquiry.
Watch: Police give Jo Cox inquiry update
“We are aware of the speculation within the media in respect of the suspect’s link to mental health services and this is a clear line of enquiry which we are pursuing.
“We are also aware of the inference within the media of the suspect being linked to right wing extremism which is again a priority line of enquiry which will help us establish the motive for the attack on Jo.
“We are keeping an open mind and I do not wish to add to the speculation as we need to ensure that we conduct a professional investigation and do not compromise the need to bring the person responsible to justice.
“Based on information available at this time, this appears to be an isolated, but targeted attack upon Jo - there is also no indication at this stage that anyone else was involved in the attack. However we will be investigating how the suspect came to be in possession of an unlawfully held firearm.”
She said the suspect had been examined by two doctors and was deemed fit to be held in detention and to be interviewed.
The charity appeal was launched from Mrs Cox’s office yesterday and a spokesman said: “In celebration and memory of Jo Cox, her friends are raising funds to support three charities closest to her heart, chosen by her family.
“The charities are:
The Royal Voluntary Service, to support volunteers helping combat loneliness in Jo’s constituency, Batley and Spen in West Yorkshire.
HOPE not hate, who seek to challenge and defeat the politics of hate and extremism within local communities across Britain.
The White Helmets: volunteer search and rescue workers in Syria. Unarmed and neutral, these heroes have saved more than 51,000 lives from under the rubble and bring hope to the region.
Members of the public can give at https:// www.gofundme.com/jocox