Simplify the following text for a Grade 7 native English-speaking person.
Original: Upon entering the Queen 's Quarters ( Okhoru Pavilion ) , the assassins `` killed three court ( women ) suspected of being Empress Myeongseong .
Simplified: When they went into the Queen 's Quarters ( Okhoru ) , they killed three women whom they thought were Empress Myeongseong .