This afternoon our Stations 2, 4 & MEDIC responded to a Carbon Monoxide call with a family of four suffering from CO symptoms. As our fire engines responded, they came across this street, in a neighborhood, blocked by cars parked across from each other. The parking prevented our trucks from reaching the scene, requiring our fire engines to back up all the way out of the street and utilize another side street to access the patients. This delayed our response to a family in need. We sounded the sirens and the horns, but no one came out to move their vehicles. This is not a good thing and really troubles us…please help us, help you.