Dart typecasting error

I have an abstract class Event and a concrete subclass that extends it called PlaceChangeEvent. Inside an event listener, I have the following code:

void onEvent(Event event) {
    PlaceChangeEvent pce = null;
    if(event is PlaceChangeEvent)
        pce = (PlaceChangeEvent)event;      // <== error is here
    else
        throw new Exception("Event is not a PlaceChangeEvent.");

    Place place = pce.place;

    presenterProvider.display(place);
}

So if the runtime type of event is PlaceChangeEvent, then I need to cast the event to that type so that I can access its properties. But I'm getting a compiler error on the typecast, stating:

A value of type 'Type' cannot be assigned to a variable of type 'PlaceChangeEvent'

Where am I going wrong, and what do I need to do to fix it?