Police in the northwestern Swiss city of Basel say they have arrested a 75-year-old woman on suspicion of killing a 7-year-old boy in the street.

Basel police said in a statement that the boy was walking home from school shortly after midday Thursday when he was stabbed. His teacher found the child lying on the ground with serious injuries and called emergency services, but the boy later died in a hospital.

Authorities said the elderly woman presented herself to prosecutors "and informed them that she had attacked the child."

Police said they are still investigating the circumstances and motive for the attack, and are appealing for witnesses.