Newspaper headlines: 'An act of pure evil'
Many front-page headlines use US President Donald Trump's words to describe the Las Vegas shootings: "An act of pure evil."
The Daily Mirror's headline is "Slaughter in Sin City".
The Daily Mail asks: "What turned Mr Normal into a mass killer?"
The Times describes Stephen Paddock as a retired accountant with no criminal record.
According to the Sun, he is thought to have had gambling debts.
The Daily Telegraph quotes an official as saying Paddock had a "history of psychological problems".
Despite this, the paper adds, he was able to buy his arsenal legally.
The Guardian says Las Vegas will be seen as the first major test of a president for whom the gun lobby was a key part of his electoral coalition.
The Las Vegas Herald says Paddock's massacre of music fans sent chills down every American's spine.
What distinguished his lethal attack from most mass shootings, the Washington Post says, were the size of the arsenal he smuggled into the Mandalay Bay Resort and Casino and the great height from which he shot.
For the Las Vegas Review-Journal, the massacre has tarnished the Strip's reputation as one of the safest streets in the US.
It says experts believe hotels will have to rethink security procedures.
While they cannot install metal detectors or other elements deemed intrusive without damaging the whole concept of hospitality, the paper adds, they will have to rely even more on the eyes and ears of housekeeping and front desk staff to detect unusual behaviour.
Elsewhere, there is extensive coverage of the collapse of Monarch Airlines.
The Telegraph says it understands the government was pre-warned that the airline faced financial ruin and has been planning for its collapse for a month.
The Daily Express reports that in the scramble for alternative flights passengers accused rival airlines of profiteering, with prices reportedly going up every minute as demand outstripped supply.
The Telegraph and the Sun, meanwhile, report that Brexit Secretary David Davis plans to retire in less than two years and leave Boris Johnson to steer the country through the transitional period following the UK's departure from the EU.
Friends of Mr Davis have told the Telegraph that he believes Brexit will be his "last big job".
According to the Sun, he has signalled that he has no wish to see the next phase through, saying: "Someone else can do that, Boris can do that."
Government proposals for a "deposit return scheme" for plastic bottles in England are welcomed.
The Sun thinks the plan by Environment Secretary Michael Gove to keep plastic bottles out of rivers and off beaches is worth pursuing.
Only 57% of them are recycled, it says, and must increase it somehow.
The Mail, which has campaigned on the issue, says after the charge on plastic bags and a ban on microbeads, the plastic bottles scheme would be another massive contribution to cleaning up polluted oceans, rivers and open spaces.
It praises Scotland and Wales for leading the way - and hopes England will not be far behind.