Berwan: you cast grease on a section of floor near the doorway into the hall. Both slip and fall over, sliding on the slippery floor through the open door. From the hall, you hear them shouting what you think are curses in your direction.
Those entering the house: the front door leads onto a long hallway, lit at intervals with wall-mounted lamps on each side. The light is dim -- but enough to vaguely see the shapes of two armed humanoids sliding through the doorway and coming to a stop a few feet into the hall. They shout angrily into the room behind them as they start to get up.
Those upstairs: you hear running footsteps downstairs, followed by angry shouting.