Fire broke out at flats on Lion Lane shortly after midnight on Sunday.
The three-storey building was completely burnt out and one person was led to safety but no-one was injured, Mid and West Wales Fire and Rescue Service said.
Dyfed-Powys Police said the man remained in custody and inquiries were ongoing.
Six fire engines attended the blaze with 30 firefighters and two water bowsers.
Police closed the A483, which runs through the centre of the town, until crews had extinguished the flames.
Source(s): BBC News
Date: 3 October 2021.
First Published: 19.38 BST.
