Police arrested a 19-year-old man after he allegedly assaulted his 20-year-old girlfriend in Waipahu.
The assault occurred at about 1:30 p.m. Wednesday. Police said the couple got into an argument that escalated when the suspect struck the victim, injuring her.
The suspect then threatened her with an unspecified dangerous instrument.
Police arrived shortly afterward and arrested the 19-year-old man on suspicion of first-degree terroristic threatening.