Beloit firefighters rescue a dog during a weekend residential fire.  Firefighters were called to the 1200 block of Lasalle Street a little after 10:00 a.m. Sunday.  Firefighters found heavy black smoke as they entered the house.  No one was home, but a dog was rescued and Janesville paramedics performed life saving measures.  No people were hurt.  The cause and damage amount is undetermined.