Dyfed-Powys Police were called to an address in the Elizabeth Court area following a report of domestic violence on Saturday morning.
A large number of police officers attended the property, and members of the public were asked to avoid the area.
Police have confirmed a 21-year-old man has been arrested on suspicion of inflicting grievous bodily harm.
The man has been taken to hospital to receive medical attention.
- For the latest crime and court news for west Wales, you can join our Facebook group here.
Chief Inspector Dominic Jones, of Dyfed-Powys Police, said: “I want to thank local residents for their patience while we dealt with this incident.
“I understand that such a large police presence in a residential street is concerning to see, and I’m grateful to everyone who co-operated with our officers at the scene.
“I’d like to offer my reassurance that our units responded to an isolated domestic incident, and there was no further threat posed to the wider community.
“The scene has now been released, and we will investigate the full circumstances of this morning’s incident.”
