BERLIN (AP) — German prosecutors said Friday they will charge a 27-year-old woman with murder after five of her young children were found dead at their home in the western city of Solingen.

Heribert Kaune-Gebhardt, a prosecutor in nearby Wuppertal, told reporters that postmortem examinations on the dead children showed signs of sedation and suffocation, but it was still unclear how exactly they had died.

The mother, who sent her eldest son to stay with his grandmother Thursday before attempting to take her own life by jumping in front of a train, hasn’t been questioned by police yet, officials said.

The killings have caused widespread shock in Germany.

Wuppertal police said the children’s grandmother had alerted authorities about a possible crime shortly before 2 p.m. (1200 GMT) Thursday. Officers who arrived at the family’s home within minutes forced open the door and found three girls, ages 1, 2 and 3, and two boys, 6 and 8, dead in their beds.

There were no signs of physical violence, said Marcel Maierhofer of the Wuppertal police force.

Investigators have so far determined that the woman’s 11-year-old son left for school as usual on Thursday morning. His mother later picked him up from school and told him to go to his grandmother, Maierhofer said.

The suspect also sent her mother a message stating that she “couldn’t go on” and cited marital problems with the father of her four youngest children.

“We can only speculate that the motive was the fraught marriage,” Maierhofer said.