Armed police officers closed down a Dartmouth street for hours Saturday, while investigating a situation in an apartment building.

Officers wearing bulletproof vests watched an apartment building in the 100 block of Pinecrest Drive with their rifles out, while saying little publicly.

At 8 p.m., Halifax Regional Police said officers were trying to arrest a person with an outstanding warrant. Police failed to find the person. As of the time of the statement, officers were leaving the area that had been locked down since almost noon.

Since that time, people were asked to stay in their homes or behind buildings and vehicles for safety. Some couldn't get back into their homes.

Until Saturday evening, police only said they were "conducting a police operation." It's still unknown what case they were investigating.

The tense situation was only steps away from a playground and the Dartmouth North Community Centre. Children were moved behind the centre for safety.

The view through my camera right now. Unfolding police situation on Pinecrest <a href="https://t.co/BieNRBMWhR">pic.twitter.com/BieNRBMWhR</a> —@SteveBerryCBC

EHS on standby

Nova Scotia RCMP officers arrived around 3 p.m., and were dropped off by a forensics van.

They came dressed in camouflage and bulletproof vests. RCMP have shields, guns and a battering ram ready.

That team, all in riot gear, went into in the apartment building.

A canine unit was there, and Emergency Health Services was on standby down the street.

The lay of the land. Officers have hands on the firearms, keeping people way back <a href="https://t.co/2JYmx9kn26">pic.twitter.com/2JYmx9kn26</a> —@SteveBerryCBC

Community picnic nearby

Residents and media were prohibited from going near the building and a hill for safety reasons.

Pinecrest was closed to traffic from both ends. The road has been reopened.

Less than a block away, a previously scheduled community picnic was being held. Officers put up tape on the parking lot separating the group from the scene.