Toronto Fire crews are investigating after a blaze broke out at a downtown restaurant Friday morning.

Shortly before 11 a.m., Toronto Fire was alerted about a fire at Rudy, a burger restaurant at Queen and Duncan streets.

Heavy smoke could be seen billowing from the restaurant.

Shortly after arriving on scene, fire crews said the main body of the blaze was knocked down.

No injuries have been reported.

Toronto Fire said the blaze started from the restaurant's deep fryer.

"There were employees in the restaurant and they were doing some cooking [at the time of the fire]," District Chief Brian Kelly told CP24 at the scene.

Duncan Street from Queen Street to Richmond Street is closed as fire crews and Toronto police investigate.