The bomb squad was called to a house in York on Friday lunchtime after a suspect item was discovered.
Boroughbridge Road was cordoned off and armed police were on the scene.
The road was closed from the junction with Plantation Drive and Shirley Avenue. It has now reopened.
A bomb disposal truck was parked outside houses, alongside police cars and at least one ambulance.
But the cordon was lifted after the bomb disposal squad called it a false alarm.
The investigation followed a man from York being arrested as part of investigation by Counter Terrorism Policing North East.
The 21-year-old man was arrested on suspicion of the possession of documents likely to be useful to a terrorist. He was taken to a police station in West Yorkshire for questioning.
On Friday evening he was bailed pending further enquiries.
A property was searched as part of the pre-planned investigation. Following the discovery of the suspect item at the property, the bomb squad were called in to provide specialist advice, leading to the cordon and evacuation of some residents.
YorkMix understands the suspect item was a commercial firework.
An army officer was seen carrying something in a red bag.
Then the bomb disposal team packed up their remote controlled vehicle and left, at about 1.10pm.
The drama started at 11.50am when the police tweeted:
Following the discovery of a suspect item at a residential property on Boroughbridge Road, York, the Explosive Ordnance Disposal (EOD) have been called to provide specialist advice to the police.
People gathered at both ends of the cordon watching and waiting.
Thankfully it all ended safely.