PORTLAND, Ore. (AP) _ Authorities have arrested an 18-year-old girl they say let her newborn baby drown in a tub after giving birth to him at a family reunion.

Irene Duarte of Portland went into labor before the reunion early Sunday, Clackamas County Sheriff's deputy Angela Blanchard said.

Duarte locked herself in a bathroom at her cousin's home and filled the tub with water. She then apparently gave birth to a 9-pound boy and made no attempt to take him out of the water, Blanchard said.

Relatives, who were not aware of the pregnancy, became concerned for her safety and forced their way into the bathroom. They found the infant in an empty tub with no pulse.

An autopsy determined that the baby died from drowning.

Duarte has a 2-year-old son who was released to the care of her mother. Duarte was expected to be arraigned on a murder charge.