Police charged 20 year-old Melissann Rosa with assault.
She remains in police custody unable to post $50,000 bail and is expected to be in court Thursday morning.
They say the incident happened Tuesday when the woman used what police called a "dangerous instrument" to injure her boyfriend in Kailua.
Rosa was arrested at Kailua district park and booked for second degree attempted murder.
Her 18-year-old boyfriend, whom she has a child with, was taken to the hospital in critical condition.
See the original article at: KHON2 Developing Stories
