A handgun was seized and a man arrested as police surrounded a petrol station as part of a "cross border" operation.
Witnesses shared footage of a large police presence at the Shell Garage on Edge Lane at around 8.45pm on Saturday, with officers remaining on scene for several hours.
At least three marked police cars were visible, though witnesses said there were also unmarked vehicles involved in the operation.
Today a spokeswoman for Merseyside Police said officers had arrested a 22-year-old man on suspicion of possession of a firearm as part of a "cross-border firearms operation".
A handgun was also recovered.
The man is in custody where he will be questioned and enquiries are ongoing.
Posting on Twitter, Assistant Chief Constable Rob Carden said: "Congratulations to the Matrix Firearms Team on last night’s dramatic resolution to a cross border firearms operation.
"Firearm recovered and another firearms enabled criminal off the streets of Merseyside."
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The force said it could not release any further information on the operation at this stage including which other country was involved.
Anyone with any information about a gun being used or stored should direct message Merseyside Police on Twitter or Facebook @MerPolCC or @CrimestoppersUK on 0800 555 111.