A 47-year-old man has died in Llanelli after being found injured in Coleshill Terrace this morning.
Police said he died after being taken to hospital.
They added that a man has been arrested on suspicion of manslaughter and is in custody.
Dyfed-Powys Police have closed off the road while investigations take place.
It said the family of the 47-year-old who died have been informed and is being supported by officers and appealed for any witnesses,