A magistrates court was evacuated on Wednesday morning after the discovery of a suspect package.
The alarm was raised at Guildford Magistrates Court in Surrey at about 0900 BST just as court proceedings for the day were about to start.
An envelope containing an unidentified white powder had been delivered to the court building.
Ten people who may have come into contact with the package were taken to hospital for checks but were later sent home.
On Wednesday afternoon Surrey Police said they had ruled out terrorist involvement.
A spokeswoman for Surrey Police said; "At this stage this incident is not believed to be terrorist related.
"The substance has been seized and is currently being analysed."
Emergency services were called to the scene along with members of Surrey Police's special Chemical, Biological and Radiological Team.
The spokesman said the police had applied utmost caution in dealing with the package to ensure the safety of the public and to maximise forensic opportunities to analyse the substance.
Prisoners in custody who had been due to appear before magistrates at the court were returned to their cells.
The court is expected to remain closed for several days.