Tha accident occurred at the Chase Water complex just after 10pm. The children were taken to hospital in Walsall where they were treated for burns.
The tragedy occurred as violent thunderstorms struck parts of the West Midlands, southern England and Wales, setting fire to several houses and leaving hundreds of others without power as much of Britain sweltered in the hottest temperatures so far this year.
Weather experts said the rain was likely to spread today as the heatwave comes to an end.
Firemen fought blazes at several houses hit by lightning last night. One was at East Horsley, near Guildford, Surrey, where the roof and first floor caught fire. Another was at Epsom, Surrey.
At Ventnor, on the Isle of Wight, a man making a telephone call was treated for shock after his house was wrecked by lightning. The roof and top floor of the building burst into flames.
In West Sussex, lightning hit the guard-room roof at the army base in Thorney Island, Chichester. Damage was not serious and nobody was hurt in the incident.
Police in Surrey, Sussex and Hampshire reported flash floods, trees brought down and roads made hazardous by torrential rain.
In west Wales, hundreds of homes were left without power when lightning struck an electricity transformer. At Angle, near Pembroke, the lightning demolished a chimney, sending it through a garage roof.
Meanwhile, scorching sunshine had tennis fans at Wimbledon's Centre Court sweltering in temperatures of 102F - until a thunderstorm ended play at 7.30pm. More than 250 people were treated for heat-related problems.Reuse content