Police say they are dealing with an "ongoing incident" and are urging people to avoid the area.
"As time went on we were later told that he actually had a gun and they barricaded the doors, kept us all away from the windows, and then we were told that he had hostages in the bowling alley next to us", she told the BBC.
Ms Mjeshtri said she was eventually allowed to leave after police moved her auto to a safer place.
Following the conclusion of the incident, forensics officers were examining the scene and a red Peugeot 307 auto was removed by police on the back of a vehicle transporter.
British police arrested a gunman on Sunday and freed two hostages after a near five-hour stand-off at a bowling alley.
Warwickshire police said a man had been arrested and was now in police custody.
The bowling alley operations manager also said the situation had been resolved.
Mr Amshar said he believed the gunman was an ex-husband or former boyfriend of an employee, but he couldn't be sure. It has been reported that two employees were held hostage.
The retail park in Warwickshire was evacuated during the incident, which the authorities quickly confirmed it was not related to terrorism. "Our priority is the safety of our staff and customers", he told Sky News.
The local ambulance service said an air ambulance had departed the scene and there were so far no casualties.
There were no injured people in the incident, although the Sky News claimed a person was taken by an ambulance.
Another witness at the restaurant, Laura Mjeshtri, said a waitress ran in and said the place was on lockdown.
"At about 4pm the police officer said if your auto is parked near the building we will go and get your vehicle".
Warwickshire police said a man with a shotgun has taken hostage at Bermuda Park in Nuneaton, and told people to stay away from the scene, according to the report.
Chief Superintendent Alex Franklin-Smith said: "We would like to thank local people for their patience and co-operation while officers dealt with this incident". It did not provide details about the nature of the incident.
It was quite scary at times.
Will Lang, the bowling alley's service engineer, said: "The gunman looked grubby and agitated and was waving the gun around".