DALLAS (CBS 11 NEWS) – If you have a smoke alarm in your home, you hope — and assume — it will go off in the case of a fire. But we’ve learned the most common detector out there — the one you likely have — might not warn you in time to save your family.

CBS 11’s Investigative Reporter Ginger Allen teamed up with the University Park Fire Department and deliberately set fires — the kind that could happen in your home while you’re sleeping. What she discovered about the smoke alarm that is likely in your house — even shocked these veteran firefighters.