A university building has collapsed in St Petersburg, Russia, with locals fearing at least 20 people might be trapped under the debris.

RT reports that the incident occurred at the Information Technologies, Mechanics and Optics University, while lectures were in progress.

The fifth to the second floors of ITMO University caved in.

The incident occurred while construction was underway.

The website said at least 60 people were evacuated from the building but quoted a local administrator saying as many as 21 people could be trapped.

An investigation into the possible criminal violation of construction safety has been opened.

St Petersburg’s acting governor Alexander Beglov told journalists at the scene on Saturday that 81 people were evacuated from the building.

He said there were no injuries.

Beglov said about 20 of those evacuated were foreign students attending a weekend class.

The school, known as ITMO University, is one of Russia’s national research universities.