Question: what happened to will smith's family in i am legend
[{'answer': 'died in a helicopter accident', 'provenance': [{'wikipedia_id': '6641931', 'title': 'I Am Legend (film)', 'start_paragraph_id': 7, 'start_character': 45, 'end_paragraph_id': 7, 'end_character': 74, 'bleu_score': 1.0, 'section': 'Section::::Plot.\n'}]}]