Part of Dalkey village in south Dublin was closed off on Tuesday night after a hole appeared in the road when part of it collapsed.
Pictures of the small circular hole on Castle Street, a main thoroughfare, have been circulating on social media.
In a Twitter post, Dun Laoghaire Rathdown County Council said a "small section of the road" had collapsed.
“Our road maintenance section have closed Castle Street temporarily for investigation & repair works. A traffic management plan & local diversion are in place,” it said.
Gardaí confirmed that while the issue was being dealt with by the council, it had closed off part of the road to traffic.
The nature of the hole has not been verified. However, sink holes pose a threat as while they often appear small they can give way to much larger subsistence.
One post on social media said it had appeared to be getting larger.
