Emergency crews were called to a house in Luton because of an alert over powder that was found in a parcel.
The owner of the house, in Buchanan Drive, Stopsley, called Bedfordshire Police after opening the package.
Police and fire and emergency crews attended the scene and removed the parcel from the house on Saturday.
It is not known what the substance was, but a police spokesman said the powder had been sent off for chemical analysis "as a precaution".