Ontario’s police watchdog is investigating after two people fell from a Burlington apartment.

In the early morning hours on Saturday, Halton Regional Police said officers responded to a call for reports of a man with a firearm at an apartment building on Ghent Avenue.

Police provided limited details in their release, but said as a result of their investigation, the Special Investigations Unit (SIU) was contacted and will invoke its mandate.

A spokesperson for the SIU confirmed it is investigating after a man, 29, and a woman, 24, fell from an apartment balcony. The SIU said based on preliminary information, Halton police were called at about 10 p.m. on Friday.

When officers arrived at the apartment in relation to the 9-1-1 call about a man with a gun, the SIU said when they knocked on the door of the unit, nobody responded.

Another emergency call came in about a woman who fell onto a patio below, the SIU said. Police administered CPR on her until paramedics arrived, but the SIU confirmed she died on scene.

The man then fell from the apartment’s balcony to the patio below, and was rushed to the hospital in critical condition.

“Two subject officials and three witness officials have been designated at this time,” SIU’s Kristy Denette told CTV News Toronto in a statement.

The post-mortem is scheduled for Sunday.