Armed police were scrambled following the first reported shots fired of 2021 on Merseyside.
Patrols were dispatched to Walton after reports of a loud noise at around 9pm on Tuesday night.
They found evidence the back of a home on Walton Lane had been shot at.
No-one was injured in the attack.
House-to-house and forensics enquiries have been launched and the area is being searched by police.
Appealing for details, Detective Chief Inspector Matt Smith, from Merseyside Police's specialist Firearms Investigation Teamy, said: “At this stage we are looking to speak to anyone who saw or heard this incident, and we’re keeping an open mind as to the motive and target.
"Although no injuries were caused, any weapon fired close to homes has the potential to have catastrophic consequences for people nearby."
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The gun blast is the first reported shooting of 2021.
Last year ended in a flurry of attacks, with two in South Sefton and one in Dingle, neither of which led to injuries.
But despite those incidents, 2020 saw the fewest shootings in a calendar year in two decades on Merseyside.
Following the Walton Lane shooting, DCI Smith added: “If you live nearby or were passing and hold any CCTV, dashcam or other information, let us know and we will take positive action.
"Although shootings have decreased on Merseyside, this is in no small part down to information provided in those communities affected.
"If you know where firearm and other weapons are being stored, carried or used, come forward and we will do the rest."
*Anyone with information can contact Merseyside by calling 101, or on Twitter (via @MerPolCC) or Facebook (Merseyside Police Contact Centre) with reference 21000010979.
Images or footage can be submitted here.
You can also contact Crimestoppers, anonymously, on 0800 555 111 or online here.
