A police manhunt is under way following a suspected armed incident in a building in Hartlepool town centre.
The armed response was called to Titan House, on the corner of Park Road and York Road, after reports of an armed male in dispute with a tenant.
One bystander said they understand the incident involved a shotgun.
It is believed the man was no longer inside the building when police arrived.
There were five vehicles there, two of which were armed response, and Barclays Bank and the Thirteen office were closed during the alert.
The tenant was evacuated safely from the scene and police are now hunting for the alleged armed man believed to have been involved in the incident.
A Cleveland Police spokesman said: "Police are still in attendance at Titan House, in York Road, Hartlepool, but can confirm it is not believed there is any threat to anyone inside the building or to the wider community in Hartlepool.
"People are being allowed into and out of the building, however, police are still investigating an incident which took place there this morning when they responded to someone armed with a firearm inside the building.
"An investigation has commenced to find out if this was the case, but there is no reason to believe anyone is now under any type of threat or in danger."
A bystander, a woman aged 24, who did not wish to be named, said: "Someone got a call in Thirteen to say we might have to evacuate because they think someone has got a shotgun.
"I think it is something serious."
Titan House tenant Paul Etheridge, 43, who lives on the same floor of the incident, said: "I heard a ruckus outside my door.
"Apparently the ones opposite were saying there was a shotgun waved about. All I witnessed was a fair fight."
Police officers were seen leaving the building at various intervals carrying automatic weapons, a battering ram and black metal shields. One had a video camera.
Barclays Bank opposite was closed to customers for around an hour.
A notice in the front door said it was due to circumstances beyond their control and directed customers to other the nearest branch in Billingham and nearby cash machines.
Offices of social housing landlord Thirteen next to Titan House has now reopened.