Regional police executed a search warrant at an address on Columbia Street West in Waterloo.

It happened at approximately 4:00 p.m. between Albert and Lester Streets.

Two occupants left the premise in a vehicle and another two left on e-bikes.

They were pursued by police, and all four suspects were detained: two in front of Waterloo City Hall, and the other two on Regina Street.

Four additional people were taken into custody by police as well.

On-scene was the core unit, the drug unit and a tactical team.

At least four police cruisers and the tactical team responded.

They were investigating reports of a controlled substance inside, which can be dangerous to responding officers.

“Any time we go in and we believe there’s a powdered substance of any kind, you’ll notice that the officers have a protective mask on,” said Supt. Daryl Goetz.

Police later confirmed that drugs were, in fact, found in the house, but would not confirm what quantity.

They also uncovered a rifle from the house.

Testing will be done to see whether the substances contain any deadly drugs.

Police say it is likely that some of those taken into custody will be released as they try to determine who was involved with the controlled substance within.

Several people were in the backyard of the address, some people were inside and some others lived in a second unit.

As of 6:40 p.m., four people remained in custody.

The investigation is ongoing.