Police have confirmed that gunman Derrick Bird shot dead 12 people before killing himelf in a series of shootings in Cumbria in northwest England.
A further 25 people were injured in the attacks and three remain in a critical condition. Five other people are said to be in a serious condition.
Shootings took place in at least 30 different locations in the towns of Whitehaven, Seascale, Rowrah, Gosforth and Egremont.
Police later discovered the body of Mr Bird in a wooded area near the town of Boot.
Local residents were asked to remain in their homes for a time after the initial killing was reported in the coastal town of Whitehaven.
The divorced father-of-two reportedly murdered a colleague in the centre of Whitehaven before driving through the Lake District shooting people, apparently at random.
Police said that following the shooting in Whitehaven, Mr Bird fled south along the coast, going through Gosforth and Seascale before turning inland and ending up in Boot.
Police investigating the killings described the shootings as 'truly exceptional'.
Deputy Chief Constable Stuart Hyde said two weapons had been recovered and 30 crime scenes were being attended.
'I can confirm that we've found a body in a wooded area near Boot which we believe to be Mr Bird, together with a firearm.
'Our condolences go out to families and friends of those affected by the horrific incidents that unfolded today.
'There are local people and local police who knew the people killed and injured today.'
West Cumberland Hospital in Whitehaven declared a major incident in the wake of the shootings, while the accident and emergency department at the Cumberland Infirmary in Carlisle was on standby.
No one was allowed in or out at the Sellafield nuclear processing site while the gunman was at large, a spokeswoman said.
British Home Secretary Theresa May said today's events in Cumbria were 'very serious and tragic'.
She said: 'Our thoughts are with the families and friends of the victims of these shootings.
'It's a terrible incident that has taken place in Cumbria today but I would like to pay tribute to the way in which the police and emergency services have worked very closely together to deal with this incident.'
The mass shooting is England's worst since 1987, when Michael Ryan killed 16 people in the village of Hungerford.