Updated April 17 at 11:20 a.m.
The sounds that some Sudbury residents were hearing Sunday night and early Monday morning came from a malfunctioning horn on a CP locomotive, according to CP spokesperson Mallory McCredie.
"CP deployed technicians to deactivate the locomotive horn, which was being affected by the weather," said McCredie.
Updated April 16, 2018 at 4:05 p.m.
Daniel DesLauriers sent in this video of the loud horn that was going off for about ten hours in Sudbury's west end.
DesLauriers said the horn started around 6 p.m. on April 15 and didn't stop until 4 a.m. on April 16.
Local radio station 92.7 Rock reached out to Vale but the mine reported it was not sounding any alarms.
Many residents said the horn was coming from the CP Rail yard off Lorne Street. 92.7 Rock reached out to CP Rail but hasn't received a call back.
This video was taken on Whittaker Street.
A city radio station is reporting that callers are reporting a strange loud horn sound in the city's west end.
On its Facebook page, 92.7 Rock said it has received several reports from listeners about the sound. One caller, the station reports, said he was told "CP Rail is conducting a 'resealing exercise' but was waiting on a call back from the rail line."
Police have been called to the area, 92.7 Rock said. The station also reached out to Vale, but the miner reported it was not sounding any alarms.
One person who commented on the radio station's Facebook page said the sound started around 5 p.m. Sunday.
"Didn't stop at all. Shouldn't be conducting tests or anything like that after a certain time. Also heard a louder airhorn sound for a couple seconds around midnight. It's really annoying lol."
Another person who commented reported a friend had called police about the sound and was told it was a malfunctioning horn belong to CP Rail.
This story will be updated over the course of the day.