Police were called to the Job Centre in Preston on Wednesday, after bags were left behind in the building.
Officers were called at about 1.20pm to the centre on Ring Way, following reports that a man had left two bags in the building.
The Job Centre was evacuated, and two police vehicles were seen outside.
A spokesman for Lancashire Police said a man had gone into the Job Centre and asked to use the toilet.
He was told he couldn’t and then left, but left behind a carrier bag and backpack.
Police attended, but the man had returned by the time officers arrived.
Nothing was found in the bag other than “personal items”.