KNTV Dateline NBC March 25, 2013
>> my first thought was the four people i have upstairs, i want to make sure they're not scared to death, that they're safe. >> reporter: but it was too late, the fire too intense. amanda's 911 call was heartbreaking. >> i have four children dead in the house! incinerated. >> reporter: as amanda grieved the loss of four children, she realized none of the smoke alarms in her home had sounded during the fire. >> i knew they worked. and then when it was time, they never went off. >> reporter: so why didn't they? the answer according to experts may come down to a simple frightening truth...