Firefighters are still working to determine the cause of a house fire on N. Upriver Bend Lane. Crews were called to a two-story house around 4:15 p.m. Friday and quickly upgraded the blaze to a second alarm, calling more resources to the scene. Crews on scene say one person got out of the house safely and called 911. Upriver Bend is closed as Frederick while crews work to get the fire under control. Several different agencies were responding to the fire Friday and are expecting to be on scene for most of the night to monitor the fire and investigate exactly what happened.