Simplify the following text for a Grade 6 native English-speaking person.
Original: Since the head wounds inflicted on Olga and Tatiana were instantly fatal , it is likely that Maria , perhaps only unconscious , was the sister who screamed , while Anastasia may still have been able to move and moan .
Simplified: When Olga and Tatiana were shot , they were killed instantly , so Maria was probably the one who screamed . Anastasia might still have been able to move .