Residents of the city of Haslet have reported hearing strange and unexplained noises around the city recently, but the mystery appears to have been solved on Wednesday.

Gary Hulsey, the mayor of Haslet, announced on October 31 that the city had received multiple reports of strange, loud, “low to mid-range frequency” sounds occurring intermittently throughout the day and sometimes at night. The noise was reportedly loud enough to wake up local residents while they were sleeping.

Some residents described the noise as sounding like a warning siren.

Outdoor warning sirens are typically activated during an emergency or life-threatening situation, such as an approaching tornado or other weather event, although reasons for siren activation can vary based on the community, according to the National Oceanic and Atmospheric Administration.

Mayor Hulsey confirmed that there have been no recent activations of an emergency alert or early warning system and that none of the community’s sirens are currently malfunctioning.

Speculating that the strange noises could have been caused by electric trains in the local area, city officials contacted BNSF Railway with a recording of the noise and copies of the complaints from local residents, asking them to investigate. BNSF operates a railway yard and intermodal facility in the city.

The railway responded promptly, taking responsibility for the noise.

Mayor Hulsey announced on November 1 that BNSF had identified a switch engine as the source of the sounds. A switch engine, also known as a donkey engine, is a small locomotive used for moving train cars inside a railyard or to switch them from one track to another. They are high-powered but not intended for moving cars long distances or at high speeds.

“BNSF stated this Switch Engine will be taken out of service ASAP. BNSF offers their apologies for the frustration caused by this noise for the community,” the mayor shared on social media.

Haslett residents who continue to hear the sound are advised to notify Hulsey at [email protected].