Three boys aged eight, 10 and 11 have died and another boy remains in critical condition after they fell into an icy lake near Birmingham, central England, police said on Monday.
"Three boys have tragically died after falling into the lake at Babbs Mill Park in Solihull yesterday afternoon," West Midlands Police said in a statement.
The boys suffered cardiac arrest and were rushed to hospital after being pulled from the water.
"Sadly, they could not be revived and our thoughts are with their family and friends at this deeply devastating time," said police.
"A fourth boy, aged six, remains in a critical condition in hospital."
Witnesses reported seeing other children on the lake, which froze during a cold snap that has hit swathes of the country.
"Searches of the lake are continuing as we seek to establish exactly what happened and if anyone else fell into the water," added the police.
The incident came as the UK was hit by heavy snow and freezing conditions, causing major travel disruption on the eve of a national rail strike on Tuesday that was already expected to bring the country to a grinding halt.
Arctic blast
The UK has been experiencing a cold snap for several days, with temperatures dropping to -10 Celsius degrees (14 degrees Fahrenheit) in some areas, although the Met Office said the temperatures were "not unusual for this time of year".
The service has issued yellow alerts for snow, fog and frost in several areas, including southeast and southwest England, and the north of Scotland.
London Stansted airport warned of disruption.
"Our runway is temporarily closed whilst we undertake snow clearing," it said late Sunday, with many flights cancelled early Monday.
The airport later said that the runway was open and fully operational, but that travellers should still brace for delays.
The airport is a main hub of budget airline Ryanair, which also cautioned about disruption to its flights at Gatwick, south of London.
"Due to ongoing severe snowy weather across the UK, runaways at both Stansted and Gatwick have been temporarily closed tonight (11 December), disrupting all flights scheduled to depart Stansted/Gatwick during this temporary closure period," it said.
Dozens of stranded passengers posted videos on social media showing snow-covered runways and planes stuck on the ground.
More than 50 flights were also cancelled on Sunday at Heathrow, the UK's largest airport, due to freezing fog.
Train and bus services in London were severely affected after the dump of around four inches (10 centimetres) of snow overnight, which also forced the closure of parts of the M25 orbital road around the capital, the country's busiest motorway.
Some schools were also shut.
AFP