Forecasters warn temperatures are set to plunge below zero after Storm Arwen lashed UK

Three people were killed by falling trees as Storm Arwen lashed parts of the UK with 100mph winds, leaving almost 250,000 homes without power last night.

Gales, snow and freezing temperatures wreaked havoc across the country, causing damage to buildings, road closures and train delays as forecasters warned the mercury was set to plunge below zero Sunday.

The storm's victims included a 'much-loved' primary school head teacher who was killed in Antrim, Northern Ireland, after a falling tree struck his car.

Francis Lagan, a father of four in his 40s, was head of St Mary's Primary School in Londonderry. He is believed to have been travelling with his wife and children when strong winds uprooted a tree that hit their car.

Stormont education minister Michelle McIlveen led tributes to Mr Lagan last night, describing him as 'dedicated and passionate'.

St Mary's deputy head Martina Bradley wrote on the school's website: 'It is with great pain and sadness... that I have to inform you of the untimely death of our much-loved principal Mr Lagan. May his gentle soul rest in peace.'

In a social media post, St Patrick's College in Maghera, where Mr Lagan was a pupil in the 1990s, said: 'Education in south Derry has lost a giant in his prime.'

An unnamed man died in similar circumstances at Ambleside in Cumbria, while a 35-year-old man was killed when a tree hit his pick-up as he drove through Aberdeenshire.

In Llanelli, Carmarthenshire, high winds tore the roof off an animal shelter, leading to the death a newborn puppy. Gusts of 117mph were recorded on Cairnwell in Scotland's Highlands, while flurries of snow hit the South and Midlands.

Waves up to 26ft were recorded off North East beaches as coastguards begged people to stay away from the sea, warning: 'No selfie is worth killing yourself for.'

In the Peak District, lines of abandoned cars stretched along the snowbound Snake Pass, which rises to almost 1,700ft in the Pennines. Part of the M62 near Rochdale was closed, with 120 lorries stuck in the snow after one jack-knifed.

All Avanti West Coast train services north of Carlisle were cancelled yesterday, while South Western Railway warned travellers of 'multiple trees and obstructions blocking the railway'.

Trains between Glasgow and Edinburgh were delayed after a barn was blown on to the line close to Polmont, near Falkirk.

Morning runners run around Roundhay Park, West Yorkshire despite the blanket of snow

Credit: Read more from dailymail.co.uk