A specialist disposal team was called to Todmorden after a bomb was left lying in the street.
The team from Catterick was deployed to Whirlaw Avenue yesterday after police were called at 2.50pm.
A friend of one of the residents had brought the World War Two shell from a skip yard.
Once they realised what it was they placed it in the street and called the emergency services.
A 100 metre area was cordoned off as residents from Whirlaw Avenue, Ashenhurst Road, Dineley Avenue, Mark Lane and Stile Road were evacuated.
They waited with neighbours and at Todmorden leisure centre as the disposal unit examined the shell.
After 30 minutes inspecting the bomb, the team confirmed it was empty and was taken away.
Residents were able to return to their homes at 4.30pm
It is the third time in the last six months that bomb displosal experts have been called to the town following the discovery of potentially explosive devices.