Complex sentence: The boy is bitten but not drained, the cross only half-incised, before police cars surround Penn and he is forced to leap high (appearing to fly) through a boarded up window of an abandoned building.
Split into simpler sentences: The boy is bitten but not drained, the cross only half-incised. Police cars surround Penn and he is forced to leap high (appearing to fly) through a boarded up window of an abandoned building.