Police believe fireworks were used to blow up mail boxes across Merewether in the early hours of Sunday morning.
Residents of Merewether and nearby Bar Beach were rudely awoken by loud bangs shortly after 4am.
Three letterboxes in Dent, Mitchell and Livingstone Streets were destroyed by the blasts, which sent debris flying and damaged nearby cars and houses.
Around two hours after the first explosion, a Kilgore Street resident found a suspicious item inside their mailbox and reported it to police who safely removed it.
Nobody was injured by the explosions.
Investigations are ongoing and police would like to hear from anyone who may have witnessed any suspicious activity.
