Two men were arrested following a report of a small explosion at a rural Llanfyrnach property on Friday afternoon.
No one was injured, and police officers immediately attended to preserve the scene and provided a safe cordon.
Investigations are continuing.
A Dyfed-Powys Police spokesman said: "Two local men were arrested in relation to this incident and have subsequently been given police bail while enquiries continue.
"We are grateful to those affected locally for their patience and understanding.”