LONDON — Three young boys who fell through ice covering a lake in central England have died and a fourth remains hospitalized as weather forecasters issued severe weather warnings for large parts of the United Kingdom.

Police in full uniform jumped into the water and broke through the ice using their bare hands to pull the boys, ages 8, 10 and 11, from the icy waters Sunday afternoon and rushed them to the hospital in the West Midlands, about 100 miles (160 kilometers) north of London. But they could not be revived after suffering cardiac arrest.

The fourth child, who is 6, remains in critical condition. Emergency workers searched through the night and into Monday for two other children who were reportedly with the group, though it is uncertain whether there were additional victims of the tragedy.

“It’s important to stress … that we’ve had no contact from anybody suggesting that there’s anybody else missing, but until we’re 100% certain we will be carrying on searches throughout the course of today,” West Midlands Police Superintendent Richard Harris said.

Harris declined to say whether the children were members of a single family.

The news came as the Met Office, Britain’s national weather service, issued severe weather alerts for large parts of the country. Roads in eastern and southeastern England were among the most affected. Some travelers were stuck for hours due to the closure of the UK’s busiest highway, the M25, which circles greater London.

Gatwick and Stansted airports warned of flight delays on Monday, and London City Airport said it was experiencing “some disruption” because aircraft were out of position after flight cancellations on Sunday night.

The country recorded its coldest night of the year so far in northern Scotland at minus 15.7 degrees Celsius (3.7 degrees Fahrenheit).

“Frozen lakes, ponds, canals and reservoirs can look picturesque but they can be lethal, and there are no greater warnings of this than yesterday’s tragic events,” West Midlands Fire Service area commander Richard Stanton said. “Yesterday’s incident is a stark reminder to us all of the dangers of open water, especially during the winter months.”