Calgary police have concluded an operation that saw members of the tactical team surround a residence in Sunalta for several hours after a woman reported being assaulted by multiple people.

The woman reported the assault about 6 a.m. Friday.

Police surrounded a home in the 1600 block of 12 Avenue S.W. and said four people were believed to be inside.

Officers could be heard using a loudspeaker, urging anyone inside to come out.

"They're just asking them to come out," said neighbour Michael Fournier. "'Come out with your hands up, we're here to help you.'"

Fournier said he first encountered officers when he left his home about 6:30 a.m.

"I was driving my vehicle out and there was an officer there with his gun out," he said. "It looked like they were ready for something, so they just waved me to keep going. Later on … Calgary police called me to make sure I wasn't in the building and to evacuate if I was."

Police cleared from the area about 2:30 p.m. after it was discovered there was no one in the home. The investigation continues.