The noise rang out across Port Moody into the wee small hours of Monday morning, mystifying some, annoying others, and even getting the attention of the police.

Described as both a screech and a musical instrument, the noise was the result of low temperatures and a load of sulphur being unloaded at Pacific Coast Terminals.

Typically, conveyors that assist with unloading at the export hub are quieted by a waterline.

“In the wintertime we’re not able to use that water system because if it freezes . . . it causes more damage to everything else,” explained the company’s administration coordinator Andrea Worsley.

During the coldest months of the year, the company desperately tries to avoid having to unload sulphur during a graveyard shift, Worsley added. However, as landslides are cleared and rail lines open back up, the company couldn’t delay unloading any further, she said.

“Because it was a clear, cold, cloudless night last night, the sound travelled all through the community,” Worsley noted.

The company offered apologies to the community and pledged to “minimize future disruptions going forward,” in a statement released on social media.

“This won’t happen very often,” Worsley said.