The blaze at Ardglass GAC in Ardtole Road was reported at 14:34 BST on Saturday.
The cause of the blaze in Ardglass in the early hours of Friday morning is being examined.
A 24-year-old man is in custody after a man in his 20s was stabbed a number of times in Ardglass.
A rower describes "one of the hairiest states I've ever been in" after 16 people are saved.
The crews, who are taking part in a rowing challenge around GB, are rescued near NI and Wales.
