Npower's Rainton office in Rainton has been evacuated after the discovery of a suspicious package.
The energy firm released a statement on Wednesday confirming the discovery and resulting evacuation of its Wearside office.
It said: "We can confirm that a potentially suspicious package was identified at Npower's Rainton House this morning.
Following normal procedures, the building was immediately evacuated at 10.30am and the appropriate emergency services were called to investigate.
"While investigations continue, the safety of our staff remains our absolute priority."