A New York City high-rise partially collapsed after a suspected gas explosion.

The city’s fire department said it was responding to a report of a gas explosion that collapsed an incinerator shaft in the 20-storey apartment block in the Bronx on Wednesday.

Authorities said no residential units were affected and there were no reports of injuries.

“An investigation is under way to determine the cause of this event and the extent of any damage beyond the reported exterior damage to the chimney,” the city’s housing authority said in a statement.