An early morning fire in a vacant single family home at N 45th and W Center Streets in Milwaukee is currently under investigation.  According to the Milwaukee Fire Department, this was the second fire in the same building in the past month.  The first fire happened on June 2.  This morning's fire was discovered by a passerby around 12:05 AM.  The fire apparently started in the first floor and then spread to the second.  Firefighters were on the scene for about an hour.  Damage from this fire is estimated at 20-thousand dollars.