The Ministry of Labour and City of Ottawa are investigating after debris fell off a building under construction at the Arts Court redevelopment site late Sunday night, forcing police to temporarily close two roads.

It happened around 10 p.m. Sunday, police said in a media release, when "falling debris from a highrise under construction ... made the area unsafe."

The highrise building being constructed at 60 Waller St., above a redeveloped Ottawa Art Gallery, will be occupied by Le Germain Hotel as well as condos by DevMcGill.

Waller Street was closed from the Mackenzie King Bridge to Besserer Street, and Daly Street was closed from Waller Street to Nicholas Street.

The roads were reopened by midnight after contractors secured the source of the "falling materials," police said on social media.

The City of Ottawa would not provide further details, saying only that it's investigating.

The Ministry of Labour also assigned an investigator to look into the incident.

<a href="https://twitter.com/Ottawa_Traffic">@Ottawa_Traffic</a> Waller st between Mac Bridge and Besserer is CLOSED in both directions due to a structural hazard. GW —@DutyInspector