A senior executive of British broadcaster BSkyB and his eight-year-old daughter were killed in a speedboat accident in the holiday resort town of Cornwall.

51-year-old Nicholas Milligan, his 39-year-old wife, a four-year-old boy and two girls aged 10 and 12 were airlifted to Derriford Hospital in Plymouth with a range of injuries, some of which Superintendent Jim Colwell of Devon and Cornwall Police described as “life-threatening” as well as “life-changing’’.

The family, from Wandsworth, south west London, were on a holiday in the coastal town when they were thrown from the boat which went “out of control” and struck them yesterday afternoon.

Water-skiing instructor Charlie Toogood has been hailed as a hero after he reportedly leapt into the speedboat to turn off its engine and stop it from causing further harm.

A second man, Will Jones, was also named as someone who came to their rescue.

Writing on Facebook, Harry Onslow said: “Thoughts are with those involved. horrible. well done Will Jones and Charlie Toogood. heroes.”

Maria Chase also wrote on the Web site, “We were down in Padstow today and saw the tragedy and saw a hero who saved more lives by jumping on to an out-of-control speedboat from another boat.”

In footage recorded by a witness and shown on the BBC, the speedboat is seen going around in circles before someone intervenes.

Colwell said: “Our thoughts are with the family and friends who are affected by this tragic incident.”

“I’d like to thank the members of the public who assisted with the rescue of the individuals in the water yesterday and all of the emergency services for safely and swiftly moving the casualties to Derriford. Everyone’s assistance undoubtedly saved lives.”

A joint investigation is being carried out into the tragedy by police and the coastguard.

The family were in Cornwall for the Bank Holiday week-end when the accident happened in the Camel Estuary near Padstow shortly before 4 p.m.