    Sentence 1: Before Sunday , 19 firefighters assigned to  wildfires had died on duty this year , according to Tracey  Powers of the National Interagency Fire Center in Boise .    Sentence 2: Before yesterday , 19 firefighters assigned to  wildfires had died on duty this year , said Tracey Powers  spokeswoman for the National Interagency Fire Center  in Boise .