At least 13 people have died in Britain while swimming during record-hot weather that caused wildfires, damaged railroad tracks and prompted a warning to step up efforts to fight climate change, Reuters reported.

The London Fire Brigade experienced its busiest day since World War II on Tuesday, when temperatures topped 40C for the first time, leading to fires that destroyed dozens of homes in the capital and set fire to dry pastures near railroad tracks and roads.

Thirteen people lost their lives after "getting into difficulty in rivers, reservoirs and lakes while swimming in recent days — seven of them teenage boys," British minister Kit Malthouse told parliament on Wednesday.

At least 41 properties were destroyed in London and more than a dozen in other parts of Britain, the minister added.

Many trains from London to northern England were delayed or canceled Wednesday after heat from the fires sagged heavy railroad tracks and damaged signaling equipment and overhead lines.

Central England recorded a new temperature record of 40.3C on Tuesday, and 34 locations surpassed the previous high of 38.7C recorded in 2019.

At the same time, the national government acknowledged that it will take years to upgrade infrastructure to deal with the heat wave.

Stephen Belcher, head of science and technology at the Met Office, said that unless greenhouse gas emissions are reduced, similar heat waves could occur every three years in Britain.

At one point on Monday, two airport runways were forced to close due to pavement damage. Power companies faced outages as the heat scorched their equipment, many schools closed early, and zoos struggled to keep pets cool.