Several downtown roads have been closed after some sort of explosion sent a manhole cover five feet into the air in the St. Lawrence Market area, Toronto Fire says.

The blast happened on Church Street just north of The Esplanade at around 9:30 a.m.

According to Captain Michael Westwood, there was heavy smoke coming from the manholes in the area following the blast as well as the sounds of rumbling.

It is not clear what caused the blast but Toronto Hydro tells CP24 that it is not the result of a hydro vault fire, as there are no outages in the area.

Toronto Hydro says their crews have ventured underground and have located a burnt cable that will need to be replaced.

That work could take the better part of this afternoon, Toronto Hydro says.

Firefighters, meanwhile, remain on scene but are only there on standby.

Church Street is currently closed at Front Street.The Esplanade ws closed from Market Street to Church Street but reopened at 1:30 p.m.

No injuries have been reported.