A 21-year-old man has been charged with manslaughter today after he confessed to fatally assaulting his 5-month-old son in Kapolei, Honolulu police said.

Prosecutors charged Huakai Kalamau today with manslaughter, a class A felony punishable by up to 20 years in prison.

His bail is set at $300,000.

Police said the unresponsive baby was taken to an area hospital Monday night where he was pronounced dead. An autopsy revealed the victim sustained “acute internal traumatic injuries,” police added.

During an investigation into the baby’s death, police said the father confessed to assaulting his baby.

Police arrested Kalamau Tuesday night on suspicion of manslaughter.

Details on the circumstances surrounding the deadly assault were not immediately available.