side of caution and waiting for the fbi to see if they'll take over the investigation or we will and testin materials. >> reporter: they washed their hands and change their clothes. they won't have to go to hospital, they were released a short time ago. we still don't know the entire content of the letter. a person holding a grudge swuns in the office or at the doctor. that'll be with further investigation. live with ktvu channel 2 news terra. >>> ktvu alex tell us why this fire is raising some red flags for investigators. >> this early morning fires sent huge flames shooting into the air. this is a cell phone video taken by a neighbor in the moment when the first firefighters arrived. >> the heat was just intense. >> we were just trying to get out of the way. >> this fire began around 2:30 in a vacant house around hudson avenue. then burn through an open lot and eventually set fire to the second house. this is where allen and her family were sleeping. her granddaughter woke her up. >> get up and get out. so i just grabbed my purse and t . that's all i know. >> their home is sadly damaged b