Investigations into what made a taxi driver shoot 12 people dead in Cumbria may centre on a family row, reports suggest.
Derrick Bird, 52, embarked on a rampage that began near Whitehaven and ended when he turned a gun on himself.
It has been reported he may have been involved in a dispute over a will, and police have confirmed solicitor Kevin Commons is among the dead.
Eleven people were injured as Bird drove around shooting indiscriminately.
Eight of those are being treated at Whitehaven's West Cumberland Hospital and the Cumberland Infirmary in Carlisle. All are in a stable or comfortable condition, said the NHS.
The remaining three have been allowed to leave hospital.
Police said Bird had firearms licences, which he is understood to have held for 20 years, and Home Secretary Theresa May has since confirmed the weapons used in the shootings were held legally.
Two weapons have been seized by police and are being examined by forensic experts. These are a shotgun and a .22 rifle fitted with a telescopic sight.
The Cumbria force are now involved in what is likely to be their biggest ever investigation, which includes 30 crime scenes.
Speaking in the Commons Ms May said, if necessary, Cumbria Police would be provided with additional funding for their investigation.
She also said local authorities and charities in the area may receive extra support.
The prime minister and home secretary are due to visit Cumbria on Friday.
Detectives said they do not expect to find any more bodies, but are following up more than 1,400 calls from people including witnesses and concerned friends and relatives.
One of the key questions is what might have caused Bird to act in the way he did.
A possible theory is that he had been involved in a dispute with his family over a will, other reports suggest he had fallen out with fellow taxi drivers after he believed they had taken work from him.
A friend reported a brief conversation he had with the taxi driver the night before Wednesday's massacre, which ended with Bird warning: "You won't see me again."
The following day Bird is reported to have left his home in the village of Rowrah and begun the carnage by shooting dead his twin brother David, at his home at High Trees Farm, Lamplugh.
He then travelled to Frizington, where the family's solicitor was killed on his driveway in Frizington Road.
Kevin Commons, aged 60, worked at KJ Commons solicitors which has offices across the region.
Next, Bird drove seven miles to Whitehaven where he shot dead taxi driver colleague Darren Rewcastle before heading through villages and countryside in west Cumbria, apparently choosing his targets at random.
Retired Sellafield worker Kenneth Fishburn, who was in his 60s, was shot dead in Egremont, while Susan Hughes - who was also in her 60s - was killed while carrying her shopping in the town.
The gunman then moved on to the village of Wilton and murdered retired couple James and Jennifer Jackson, who had been talking to others in the Town End Farm area.
Part-time mole catcher Issac Dixon, aged in his 60s, was the next to be targeted. He was shot and killed at the edge of a field in Carleton while he talked to a local farmer.
Then in Gosforth, Bird shot dead rugby league player Garry Purdham at point blank range as he worked in a field.
Mr Purdham played semi-professionally for Workington and Whitehaven, and was the older brother of Harlequins skipper Rob Purdham.
There were further shootings in Seascale, where cyclist Michael Pike, 64, and Jane Robinson, who was in her 70s and delivering Betaware catalogues, were both killed.
Dr Barrie Walker, a local GP who was called to the scene of the Seascale shootings, said two young girls had witnessed Mr Pike's killing.
He said: "He was shot twice by the perpetrator and these two girls were watching it and he looked straight at them and these kids were mute for the next two hours. They couldn't speak for the next two hours."
He added: "It's a beautiful area... to see this kind of carnage in the streets. There was blood running in the gutters of the streets of Seascale and this is just something you don't expect."
The twelfth victim is understood to be 23-year-old estate agent Jamie Clark, who was driving through Seascale when Mr Bird opened fire at him.
It was unclear whether he died from gunshot wounds or the resulting crash.
His employers - lettings firm Belvoir - have paid tribute to "one of the nicest lads you could ever hope to meet".
Floral tributes have been laid at the scenes of the shootings across the county.
Before Bird was found dead in Boot - shortly after crashing his car near the River Esk - his rampage had spanned about 25 miles.
Don Reed was one of the first people Bird opened fire on in Whitehaven - but luckily he survived with a wound to his back.
Mr Reed, a taxi driver who knew Bird, said: "I looked up and I saw Derrick Bird's taxi pull up at the back end of the taxi rank.
"The next thing was he shouted Darren Rewcastle and he walked in the middle of the road, and then he just opened up with a single-barrelled shotgun with a telescopic sight on it.
"He then drove up by me and just pointed it at me, and I just took a flying dive and he caught me in the back. I went on the floor and then I crawled along the taxi rank.
"I was going to apply first aid to Darren, but when I saw Darren, he was gone.
"I crawled round and Derrick Bird was walking towards me with this shotgun."
Mr Reed crawled near the taxi rank and opened all the car doors to get some protection from the shotgun blasts.
However, when a friend shouted at Bird, the taxi driver got back in his vehicle and drove off - shooting another man in the face as he left.
Cumbria Police's Deputy Chief Constable Stuart Hyde said more than 100 officers were involved in the investigation.
"We are still at a very early stage in our investigation and we are not able to really understand the motivation behind it - or establish whether this was a premeditated or random attack.
"We are working hard to support the families of those involved and our focus is now on gathering as much evidence as possible to build up a clear picture of what happened this morning.
"We want to clearly understand his possession of these weapons, what happened, what went wrong and why he decided to use these to shoot people.
"What we want to do is ensure we understand what has happened, speak to people about him, his life, what has gone on in the last few days, what might have turned somebody into a killer."
Counselling sessions are being offered at the psychology department of the West Cumberland Hospital for anyone affected by the shootings.