DES MOINES, Wash. -- A 9-month-old baby drowned in the bath tub when his mother stepped away to get a cup of coffee, according to Des Moines police.

The incident happened around 9:30 a.m. in a Des Moines apartment complex on Marine View Drive Tuesday.

VIDEO: Neighbors React To Baby Drowning

The 23-year-old mother told detectives that she stepped away during her baby’s bath for a cup of coffee and to get the boy’s breakfast.

When she returned, she said he was underwater and not breathing. Police do not know how long she was out of the room with the baby left unattended.

"South King County and medics arrived within about 5 minutes. They were unable to resuscitate the baby," said Sergeant Bob Collins of the Des Moines Police Department.

Des Moines police are conducting a death investigation, although they cannot say if it will lead to any criminal charges.

The mother of the child lived with her boyfriend, who police said is not the baby's father. He was at work this morning.