A family of four escaped serious injury when youths threw a powerful firework through an open window.
The attack was one of many acts of trick-or-treat terror which kept emergency services busy last night.
Teacher David Etherton, of Ladies Mile Road, Patcham, Brighton, heard a crash and children running away moments before he found the Mega Air Bomb in his downstairs bathroom.
Mr Etherton, deputy head at Southgate West Middle School, Crawley, said: "I went into the bathroom and there was a firework on the windowsill.
"I could smell it so I shut the door, waited for 20 minutes, then went in there and found the firework. It had burned a hole in the sill."
The fuse on the air bomb was burning when it was thrown but the firework did not ignite.
Mr and Mrs Etherton's two young children, aged one and three, were asleep when the firework was thrown.
Firefighters were called at 8pm to remove it.
Police dealt with dozens of other calls from residents who were victims of Hallowe'en pranks.
In Graham Avenue, Patcham, fireworks were put into a Royal Mail letter box. They exploded, blowing off the door and scattering post over the street.
In Goldstone Road and Goldstone Crescent, Hove, several residents reported car windows being smashed after they refused to answer their doors.
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