The centre of Sheffield came to a standstill during rush hour traffic on Tuesday after a suspect bag was found outside official buildings.
Army bomb disposal units were called to Bridge Street after a package was found near Home Office buildings and the police headquarters in the city.
A 100m cordon was put around the site with main bus routes and roads closed.
Police said the city was "gridlocked" for two hours with diversions in place. The bag turned out to be a empty.
A spokesman said two controlled explosions were carried out at the scene which was also near the city's magistrates court.