Four men escaped unhurt when a lightning bolt “exploded” the roof of their house in Spalding.
Next door neighbour John Blythe, of Stonegate, said slates were hurled 30-40ft away – some hitting his property – and anyone passing would have been “cut to shreds”.
The ferocious strike on Thursday teatime hit power supplies to neighbouring homes, “melted” appliances like televisions, knocked out phone lines and made the ground shake.
Mr Blythe thought his own house had been hit until he went outside and saw next door’s roof gone.
He said: “It sounded just like an explosion. The whole roof has gone. It’s massive damage that’s been caused by one bolt of lightning.”
The four men in the house went across the road to the home of Gary and Debbie Inman, where they were offered a drink which they declined.
“They didn’t stay long,” said Mrs Inman.
Her son, Max (11), saw the lightning bolt hit.
Mrs Inman told the Free Press: “He said there was a bright yellow flash and then the whole roof lifted off and it came back down on itself.
“I was in the back, but I felt the ground shake like a lot of people did.”
The Blythes were counting the cost of the damage to their home, which included a melted television and a gas boiler put out of action, but say someone else nearby had a lucky escape.
Mr Blythe said: “One of the young ladies next door was on her computer and bits came out and hit her in the face.”
Police sealed off the road while firefighters made the house safe.
Spalding and Bourne crews also put out a loft fire when a house being renovated at Tunnel Bank Farm, Bourne, was hit by lightning just after 4pm – they stopped the fire spreading.