EDMONTON -- Police say a suspect who hid for hours inside an Edmonton sewage treatment plant has been arrested after an officer found him inside a duct.

Police spokesman Scott Pattison says the suspect was chased to the Goldbar Wastewater Treatment plant early Friday morning following an alleged domestic assault at a fast-food restaurant in Sherwood Park east of the city.

The police and its helicopter tracked the stolen vehicle he was driving, which went into the river near the plant.

Pattison says a tactical officer who was searching a tunnel spotted the suspect over the lunch hour when the suspect poked his head out of the duct.

He says the officer ordered the suspect to stand down, and he was arrested without incident.

It's unknown how the suspect got into the plant.

"He was crawling around up in the ductwork," Pattison said. "There are tunnels that connect buildings at that facility."

Epcor operates the plant, which runs 24 hours a day. Spokesman Tim LeRiche said employees who were in the plant were safe and that the plant continued to operate normally.

LeRiche noted the plant is "secure and is completely fenced, including barbed wire along the top of the fence."

Pattison said a canine unit tracked the suspect's scent and his footprints over a perimeter fence and into one of the plant's buildings.

Police have not released the suspect's name. Pattison said he'll face charges from the alleged assault as well as the following chase.