The source of a mysterious mist that sickened two train workers as their train passed through downtown Suffolk on Saturday evening is still undetermined, according to city officials.

City spokesman Tim Kelley said on Monday that Suffolk Fire & Rescue and the Virginia Department of Emergency Management responded to the scene Saturday evening but were unable to locate anything. The identity and source of the mist, therefore, remains undetermined.

The incident started about 8:51 p.m. Saturday when a Norfolk Southern freight train stopped at Lake Meade Drive and Lake Cohoon Road after two workers on the train became ill, according to a city press release.

They said they became ill after the train passed through what was described as a mist at the Saratoga Street rail crossing. They were taken to Sentara Obici Hospital for evaluation.

Norfolk Southern officials called in a private hazmat company to evaluate the train before releasing it to continue traveling, the city press release stated. No sign of the mist was located in the Saratoga Street area.

The incident remains under investigation.