A 37-year-old Maryland woman has been arrested for allegedly drowning her 3-month-old infant in a bath.

Mackenzie Rose Colgan called 911 and said she had killed the baby, Montgomery County Police said. First responders arrived and took the child to a hospital, but the baby was ultimately pronounced dead.

Colgan has been charged with first degree murder.

A probable cause statements says that Colgan took the baby girl upstairs to bathe her just after 11:30 a.m. on Sunday, according to Law&Crime. About 20 minutes later, Colgan came downstairs and said the baby was dead. The child’s father told Colgan to call 911 and ran upstairs to give the baby CPR.

In an interview with detectives, Colgan reportedly said that she woke up Sunday morning with a plan to “end everything” — she was going to kill both her children and her husband, she said.

When she took the infant upstairs, she said she filled a baby bath with water and then put that into a larger tub.

“She then said that she turned the baby to face away from her and held the victim’s head under the water until she knew the victim was dead,” police wrote in the affidavit.

Then, she said, she went to a bedroom and planned to jump out of a window. Once she got onto the ledge, however, she changed her mind and went downstairs, where she told her husband what she’d done.

Colgan, a licensed counselor, is slated to undergo a mental health evaluation prior to her first court appearance.

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