POLICE were last night investigating what sparked gunman Derrick Birds killing spree amid reports he was involved in a bitter family feud.

Reports suggest Bird's first victim was his twin brother David who he had rowed with over a will.

The 52-year-old taxi driver then embarked on a three-hour massacre through Cumbria, killing 12 people including former colleagues and random passers-by. Finally, he killed himself.

It was claimed another of the dead was the family's solicitor, Kevin J Commons.

David Whyte, a business associate of Mr Commons, tonight said he expected the firm to be making a statement this morning.

Britain's worst mass shooting since the 1996 Dunblane tragedy began when the divorced father-of-two shot fellow taxi drivers in the town of Whitehaven yesterday morning, killing at least one.

It ended just over three hours later with the discovery of his body 20 miles away in woods near the hamlet of Boot after a frantic manhunt. Officers recovered two weapons.

Three of those injured in the shootings were in a critical condition in hospital last night and another five were said to be serious.

The scale of the massacre stunned the normally peaceful community.

Deputy Chief Constable Stuart Hyde, of Cumbria Police, said there were 30 separate crime scenes and described it as "the most exceptional, challenging incident the county had faced in a long time".

The force has launched a full and thorough investigation into the tragedy, looking at Bird's history, access to guns and motives for the shootings, he said.

Last night the Queen said she was "deeply shocked" by the shootings and shared the nation's grief and horror.

Those who knew Bird said he was a quiet, normal bloke with two grown-up sons - one of whom had just become a father - who lived alone in Rowrah, near Frizington, Cumbria, and liked tinkering with his car.

But his friend Peter Leder said that Bird had chillingly told him: "You won't see me again."

The rampage began at about 10.30am when Bird produced a gun and shot fellow taxi drivers in Duke Street, Whitehaven, killing Darren Rewcastle.

One Whitehaven cab driver said he understood three taxi drivers had been shot, two fatally.

The man, who did not want to be named, claimed an argument broke out between Bird and the other three men last night at the Duke Street taxi rank.

He said: "All of the taxi drivers were friends. But I heard last night there was an argument on the taxi rank.

"I don't know what caused it, but something must have happened last night. Derrick Bird took off in his car and went home. I don't know what time of night it was."

Glenda Pears, boss of L&G Taxis, said: "We just don't know what's happened. The lad that's been killed was friends with him. They used to stand together having a craic on the rank.

"He was friends with everybody and used to stand and joke on Duke Street."

People described their terror as Bird passed through the town with the shotgun hanging out of the window of his taxi.

One witness said the gunman drove alongside him at traffic lights by Whitehaven police station in Duke Street.

Alan Hannah, 68, of Great Broughton, said: "A car pulled up on the left, stopping at the lights.

"I saw a man with a large shotgun and his windscreen was smashed. I drove through the red light to get into Lowther Street and get out of the way. I got home safely but was very shaken."

Police said that after leaving Whitehaven, Bird travelled south along the coast, killing and wounding people in Egremont, Gosforth and Seascale before turning inland and ending up in Boot.

He murdered Garry Purdham, a popular player with Workington Town rugby league club, as he worked in a field near Gosforth.

Mr Purdham, a farmer's son, was in his early 30s with two young children, according to neighbours.

David Southward, a county councillor for St Bees and Egremont, knew several of the victims.

"Garry Purdham was a well-known local sportsman. He was the same age as my son, which really brings it home to me.

"I also knew a gentleman who was killed in Seascale.

"He was a former colleague who I haven't seen for years."

Rod Davies, landlord of Gosforth Hall Inn, said the close-knit community was shaken by the tragedies.

"There's a lot of very strong feeling of absolute shock. There's a lot of fear - a lot of people are expecting to hear names of people they know," he said.

In nearby Seascale, Bird shot dead Jane Robinson, 66, just yards from the home she shared with her twin sister, Barrie.

He also killed retired trade union organiser and father-of-two Michael Pike, 64, who was out cycling.

Seascale GP Barrie Walker said young children witnessed the shootings.

"People were out on the streets on what was a bright summer day," he said.

"This is a quiet area - we are country GPs, we do not have gunshot wounds to deal with."

Boot Inn landlord Sean King said that fellow publican Harry Berger, who runs the Woolpack in Boot, was shot in the arm in Seascale and was recovering in hospital.

A member of staff at the Woolpack said a girl received minor buckshot wounds.

An Egremont resident described finding the body of another of Bird's victims - a woman in her 60s carrying shopping bags - outside his house.

Billy Boakes, 23, did not see the shooting but heard two gunshots at about 11am.

He said: "I thought nothing of it at first, I thought it was just a trailer banging as it went down the lane, but then I looked out the front window two minutes later and saw a car and a push bike parked up and thought there had been an accident.

"I went outside and saw the body of the woman lying outside my house."

Another Egremont resident said she saw the body of a man, thought to be in his 60s, lying on a road bridge in the town.

Bird crashed and dumped his car in Boot, continuing on foot into the woods where his body was found at about 1.40pm.

The vicar of Eskdale, the Rev Anne Baker, said she heard that two people had a lucky escape when they approached the killer after the crash to see if they could help.

Sellafield nuclear reprocessing plant was closed while the gunman was on the run.

Early reports suggested Bird also killed his mother, but police later confirmed that she was alive and was being looked after by her family.

After a police cordon on The Bridge in Egremont was lifted, flowers were left at the spot with a card saying "RIP Ken - tragically taken but not forgotten".

The card was signed "your girls and Marc - Ladbrokes".

People nearby said the victim was Kenneth Fishburn, a retired security worker at the Sellafield plant.

Karl Scarr, 44, said: "He worked on the gates at Sellafield. After he retired I used to see him in town. He always said hello, he was a nice guy."

About 100 yards away a muffled bell tolled at St Michael and St Mary parish church as about a dozen residents gathered for the evening service to remember those killed.

The Rev Richard Lee said: "This is a very close community and everybody will be touched by this tragedy."

Last night in Whitehaven town centre, police lifted a cordon on Duke Street where Mr Rewcastle was shot dead.

Scene of crime officers had been examining the scene earlier today while Mr Rewcastle's body lay covered.

Friends and well-wishers had left flowers at the scene, paying their respects to the popular taxi driver.

One tribute said: "RIP Darren, cruelly taken from us on this day that will be remembered as a tragedy.

"Sorely missed and never forgotten. I hope you have taken that great sense of humour with you. Love forever, Siobhan XXX Kelly XXX."

Another said: "To Darren, going to miss you mate. You'll never be forgotten. From Linda (Ding Dong Taxis)".

Another read: "RIP all the victims of today's horrific events XX."

Finally, the last bunch of flowers said: "To Darren, RIP, from Jimmy Taxi".

Cumbria Police set up a casualty bureau line on 0845 3300 247 and appealed for anyone with information about Birds movements over the last 24 hours to contact them.

People who are worried about friends and family can call a police helpline on 0800 0960095.

As he began his first Prime Minister's Questions today, David Cameron said the House of Commons would be alarmed and shocked by the events unfolding in Cumbria.

He said: "When lives and communities are suddenly shattered in this way, our thoughts should be with all those caught up in these tragic events, especially the families and friends of those killed or injured."