Complex sentence: The children's unusual abilities and Emma's obsessive attachment to Mimzy soon alert their parents and schoolteachers to the devices; later, a power black-out of the entire Pacific northwest caused by the toys alerts the FBI to their activities as well.
Split into simpler sentences: The children's unusual abilities and Emma's obsessive attachment to Mimzy soon alert their parents and schoolteachers to the devices. Later, a power black-out of the entire Pacific northwest caused by the toys alerts the FBI to their activities as well.