Police are seeking an arrest warrant for a woman in her 40s accused of killing her recently born 7-month-old twins, citing the stress of caring for them alone, officials said Tuesday.

The suspect was taken into custody on Monday after she called police at 12:40 p.m. to turn herself in. Earlier in the day, the woman allegedly suffocated the infants with a blanket at around 8:30 a.m. in their home in Yeosu, South Jeolla Province, while her husband was at work, according to Yeosu Police.

Authorities said no external injuries or signs of abuse were found on the babies, when police went to the woman‘s residence in response to her call.

According to police, the new mother admitted to struggling with stress raising the two newborns during questioning. She had previously received counseling for depression but had not been diagnosed with medical depression.

The police plan to conduct an autopsy to check the exact cause of the twins’ death. Investigators are reviewing whether her husband has any responsibility in the case.

A court hearing to determine whether the woman will be formally arrested is scheduled for Wednesday.