The mother of the gunman who killed 20 children and seven adults in America’s worst school massacre, was a gun-proud “survivalist” preparing for economic collapse, it has emerged.

Nancy Lanza, whose gun collection was raided by her son Adam for Friday’s massacre at Sandy Hook school, was part of the “prepper” movement, which urges readiness for social chaos by hoarding supplies and training with weapons.

“She prepared for the worst,” her sister-in-law Marsha Lanza told reporters. “Last time we visited her in person, we talked about prepping – are you ready for what could happen down the line, when the economy collapses?”

It also emerged that Mrs Lanza had spoken of her fears less than a week before the attack that she was “losing” her son. “She said it was getting worse. She was having trouble reaching him,” said a friend of Mrs Lanza who did not want to be named.

Police disclosed that the 52-year-old had five legally registered guns – at least three of which her 20-year-old son carried with him. Most victims were shot with an assault rifle, while Lanza also carried two handguns and left a shotgun in his car.

President Barack Obama was on his way to Connecticut to comfort families of the victims, amid mounting pressure for political action in Washington on gun control.

Democrats are preparing to introduce a new bill to ban assault rifles , but the difficulty of achieving any consensus was well illustrated after one Republican congressman said staff at the school should have been armed to protect themselves.

Fresh details emerged of the massacre which has caused shock waves across America as well as internationally.

Lanza was reported to have wiped out one complete class of six and seven-year-olds along with their teacher. Dr H Wayne Carver, Connecticut’s chief medical examiner, said the injuries were the worst he had seen in his career with some of the children shot 11 times.

One of the victims, six-year-old Dylan Hockley, was the British-born son of a couple who moved their family to Connecticut from Hampshire two years ago.

His mother, Nicole, had described the area as “a wonderful place to live”, with “incredible” neighbours and “amazing” schools”.

Dannel Malloy, the Connecticut governor, said the death toll might have been much greater and Lanza may have planned to kill even more.

“We surmise that… he heard responders coming and apparently at that, decided to take his own life,” Mr Malloy said.

Candlelit vigils were held over the weekend for the victims.

One was for Victoria Soto, a 27-year-old teacher who was killed after telling Lanza the children were in another room, allowing some of the children to escape. “She was selfless – selfless,” Jessica Zrallack, a former schoolmate, told The Daily Telegraph.

Newtown’s residents were forced to endure fresh anguish yesterday, when a Roman Catholic church that has become a centre of support for the grieving, was evacuated following a telephoned-in security threat. St Rose of Lima was later given the all-clear.

Mr Obama was preparing to visit the town last night in order to comfort the families of those killed and speak at an interfaith vigil.

The president, who failed to deliver on a 2008 election promise to reinstate an assault weapons ban, is now under mounting pressure from within his own party to throw his political weight behind new laws.

Despite the outpouring of national grief, the Bill is likely to be highly divisive; Congress has not passed significant gun legislation for almost 20 years, amid partisan gridlock.

A poll by CNN in August found that 57 per cent of Americans favour a ban on semi-automatic assault weapons, while 60 per cent favour outlawing high-capacity ammunition clips.