Armed police, dogs and the force helicopter swooped on Hucknall town centre on Thursday afternoon when gun shots were heard.
Officers in full riot gear and armed with automatic weapons were seen by shopkeepers swooping into the High Street at around 2.45pm.
Sections of the street were cordoned off between Watnall Road and Station Road as police cars barricaded the roads and stopped people from entering the area.
Shop staff, customers and office workers were told to stay inside, move away from the windows and lock all doors as the scene unfolded.
“We saw people gathering outside the shop and wondered what was happening,” said Costa assistant manager, Rachel Liffen. “We went to have a look and saw police with riot gear and automatic guns coming out of a big black van and running up the street.
“Somebody said they had heard gun shots but we didn’t hear anything.
“It was really quite scary.”
As social media was stormed with suggestions that an armed robbery was happening at one of the High Street banks, a Hucknall police spokesman moved to reassure residents that this wasn’t the case.
Staff at neighbouring estate agents Haart’s said they were told by police to stay inside, away from the window and lock all doors.
Sales negotiator, Holly Carnill, took photos on her mobile phone of the armed police as they arrived.
Speaking as the incident unfolded, Holly said: “They have cleared the street and blocked off the roads.
“We don’t know what’s happening but I didn’t expect this when I came into work today.”
With the incident happening a short distance from Beardall Street Primary School, it is believed pupils were kept in school longer as a precaution.
Just over an hour after the incident unfolded, police were allowing customers who had been seeking refuge in the shops to be escorted to safety as business owners were told to shut up shop and leave.
As the Dispatch went to press, Nottinghamshire police confirmed officers were called to the Spot On snooker club in Vine Terrace at 2.40pm ‘following a report of a man acting suspiciously’.
“Officers asked people to stay inside as a precaution and to avoid the area,” said a spokesman.