Atlantic Canada province says dam could breach, tell residents to get out.

The heaviest rain to hit the Atlantic Canadian province of Nova Scotia in more than 50 years triggered floods causing "unimaginable" damage, and four people are missing, including two children, officials said on Saturday.

The storm, which started on Friday, dumped more than 10 inches on some parts in just 24 hours - the same amount that usually lands in three months. The resulting floods washed away roads, weakened bridges and swamped buildings.