Herts Fire and Rescue has confirmed a fire that filled atria Watford units with smoke is believed to have started accidentally.

Two engines from Watford and one from Garston were called to reports of a blaze in the shopping centre’s basement at 8.53am (March 4).

Crews found the fire in a trash compactor, but could only gain access by removing a storage unit with a winch while trying to stop the spread. It was fully extinguish by 11am.

Watford Observer: Evacuated shoppers outside atria Watford.Evacuated shoppers outside atria Watford. (Image: Bev Cassidy)

Portable ventilation fans were then used to clear smoke from the building, as some units in the centre had "smoke logging".

Two breathing apparatuses, a hose reel, and a fog spike were also needed.

Just before 12pm, the service confirmed that the fire is believed to have started accidentally.

Watford Observer: Evacuated shoppers outside atria Watford.Evacuated shoppers outside atria Watford. (Image: Bev Cassidy)

As Herts Fire and Rescue tackled the emergency the alarms sounded inside.

Shutters went down for some shops and doors were taped up, while customers and store staff were evacuated from the side of the centre north of Queens Road.

They were then left to stand outside in High Street and Queens Road while they waited for atria to reopen.

Watford Observer: Evacuated shoppers outside atria Watford.Evacuated shoppers outside atria Watford. (Image: Bev Cassidy)

Businesses in the other part of atria Watford were able to continue operating as normal.

Shoppers were able to go back inside the previously closed section from around 10am as staff began reopening some of the closed shops.

An atria spokesperson said: “We can confirm that part of atria Watford was temporarily evacuated this morning - for approximately one hour - as a precaution, following the outbreak of a small fire in the basement of the centre.

"Our team acted swiftly, the fire was quickly extinguished and we are now re-open as usual.”