Police arrested a man after he allegedly assaulted his ex-girlfriend, possibly with a box cutter, in Kakaako early Wednesday.

Police said the suspect and the victim were involved in an argument at an establishment at about 12:30 a.m. when he brandished a small and sharp dangerous instrument.

He struck the victim, cutting her head. The injury was non-life-threatening and she was transported to a hospital in stable condition.

Police said a witness saw the suspect use slashing movements toward the victim. Though witnesses couldn’t positively identify the type of dangerous instrument the assailant used in the attack, responding officers recovered a box cutter at the scene.

Police arrested the suspect on suspicion of second-degree assault.

Lifeguards rescue 2 boaters off Portlock

Lifeguards rescued two men after their boat ran into trouble at the China Wall surf area off Portlock in East Oahu, according to Honolulu Ocean Safety officials.

At about 10:15 a.m. Wednesday, Ocean Safety rescue watercraft operators towed the 21-foot boat carrying two men in their 30s to 40s to Maunalua Bay Beach Park. No injuries were reported. Surf was reported at 1 to 3 feet, although conditions were windy.