Peter Giberson, with Dartmouth Metals, a salvage yard in the Burnside industrial park, told CBC News police asked his employees to leave the building while they investigated the reports.
Giberson said he didn't see anyone with a gun.
A worker at Dartmouth Metals was seen leaving the building under heavy police surveillance. He told CBC News that he didn't leave with the other employees because he didn't realize the severity of the situation.
The drama was still taking place at 2 p.m. AT Saturday.
The salvage yard is on Dawn Drive. An employee at another business on the street told CBC News that police told him to stay inside and that they were on lockdown.
The man said he saw police dogs heading up the street.
The drama has been unfolding since about noon.
Yolanda Biddulph was leaving the Tim Hortons on nearby Windmill Road when police blocked off a section of the street. She said she saw heavily armed police.
"They got out and surrounded the Cold Beer store, the brewery," she told CBC News.
A worker at the Cold Beer store told CBC News that he saw multiple ambulances travelling along Windmill Road.
Police are speaking to employees of some businesses in the area.