Power has been restored to 109 homes in Berkshire after fireworks were lit and thrown into an electrical fusebox.
Witnesses saw children running from the scene in Whitley Wood Road, Whitley at about 0400 GMT on Saturday.
The fireworks were thrown into a box which houses electrical fuses servicing a number of flats above the shop.
Southern Electric was forced to cut power to the homes while repairs were carried out. A spokesman said supplies were reconnected later on Saturday.
He added: "Our priority was to look at what damage was caused and repair it as fast as we could.
"Throwing fireworks anywhere is dangerous but... this has caused disruption to nearby residents and damage to our equipment."