The Honolulu Police Department investigated several assault cases Sunday, including one in Waikiki that required medical intervention.

Police opened an assault investigation early Sunday after an 18-year-old man was injured following an altercation at a Waikiki liquor establishment at around 12:20 a.m. The man sustained a head injury and was brought to a hospital in critical condition, police said.

Officers also responded after a 71-year-old man allegedly assaulted a 71-year-old woman at about 10:30 a.m. in Waimanalo. They said the woman sustained minor injuries, and the man was arrested at the scene on suspicion of second-degree assault.

HPD officers also responded to a report that a 73-year-old man had assaulted his 43-year-old girlfriend with an unidentified “metal object” at about 1:45 p.m. in Pearl City. Police arrested the man on suspicion of second-degree assault at about 1:55 p.m.