SCENES of crime officers were called to Grimsby late last night after unconfirmed reports of an incident involving three men who may have been armed.
A white tent was erected by the specially-trained officers in Castle Street, as police officers stood guard outside a bookmakers shop on nearby Park Street.
The Humberside Police helicopter was also scrambled and was seen searching overhead.
Local residents, who did not wish to be named, said they were alerted to the incident by the sound of sirens at around 9pm.
They came out of their homes to witness what they said were three men running from Park Street in the direction of Castle Street.
Two of the residents said they thought they saw a weapon, possibly a gun, although that was not confirmed at the time of going to press.
One woman said: "I was on my laptop and nearly dropped it after hearing an almighty loud bang – to me it sounded like a gun shot.
"And then after that I heard lots of sirens and the police arrived."
UPDATE: Four on the run after armed robbery at bookmakers