*Family row or work dispute among possible reasons
*Government will review UK gun laws
Whitehaven, England - Reuters - Police said on Thursday they may never be able to fully explain why a quiet taxi-driver shot dead 12 people in the scenic Lake District, in Britain's worst gun rampage for years.
Prime Minister David Cameron said Britain already had some of the toughest gun control laws in the world and there should not be a knee-jerk response to the tragedy.
Derrick Bird's shooting spree on Wednesday through sleepy towns and villages in one of Britain's top tourist spots stunned the country and left authorities struggling to find answers.
The 52-year-old, later found dead in the remote Eskdale valley after apparently turning one of his guns on himself, seemed to know some of his victims while others appeared to have been strangers, shot dead at random during a three-hour rampage.
"My officers and I are absolutely determined to get to the bottom of why this happened. However it may not be possible to establish all the answers because we cannot speak to Derrick Bird," Detective Chief Superintendent Iain Goulding said.
Eleven people suffered injuries, with most having gunshot wounds to the face. Police in the county of Cumbria said more than 100 detectives were now piecing together Bird's trail with evidence scattered across 30 different crime scenes.
Cameron, who will visit the region on Friday, said everything should be done to avoid a repeat of Britain's worst multiple shooting since 1996.
"We should be clear that in this country we have some of the toughest gun control legislation anywhere in the world," he told a news conference. "Of course we should look at this issue but I don't think we should leap to knee-jerk conclusions about what can be done on a regulatory front."
Officers are trying to work out what turned the driver, described by friends and colleagues as a nice, quiet, normal man, into a mass killer.
Fellow taxi drivers in the coastal town of Whitehaven in northwest England, where Bird worked, told Reuters he had been involved in a dispute with other cabbies the previous night.
Newspapers reported that after the row he had left saying: "There's going to be a rampage tomorrow". At least one of those killed was a taxi driver.
There have also been unconfirmed reports that a dispute over a family will might have pushed him over the edge. Lawyer Kevin Commons and Bird's twin brother David were among the dead, although David's three daughters in a statement denied any feud.
"We would like to take this opportunity to say there was absolutely no family feud. Our dad's only downfall was to try and help his brother," they said, without elaborating.
Police said they would be looking into the rumours of financial and domestic problems, adding that there was no evidence that Bird, who had previous convictions for theft, had any mental health problems.
The rampage was Britain's deadliest multiple shooting since Thomas Hamilton walked into a school in Dunblane, Scotland, 14 years ago and shot dead 16 children and their teacher. That killing led to new, stricter gun laws, including a ban on handguns.
Police said Bird, who used a shotgun and a .22 calibre rifle with a telescopic sight, had been licensed to own both firearms. The government said it would hold a review of existing gun laws when the full facts of the case were known.
Cumbria is one of the safest places in Britain, and the latest official figures show there were just four homicides in 2008/9. In 2006/7 there was none.
- REUTERS reg
