LONDON, ONT. -- A large number of police vehicles and officers in tactical gear made fore some tense moments in the area of Regent Street at Adelaide Street on Thursday afternoon.

Officers carrying shields could be seen at the front door of 596 Regent St. while the tactical unit surrounded the home.

Armoured vehicles and canine units were also in the area on standby as officers entered.

Witnesses tell CTV News that at one point a megaphone was used with police asking someone to "come out."

After a lengthy search, officers cleared the area around 1:30 p.m. after no one was found in the house.

OPP said two people were arrested then released unconditionally, while a third person is being sought in the investigation.

A quantity of pills believed to be oxycodone were seized.

Regent was closed at Adelaide, but has since reopened.

The investigation is ongoing.