Police say a man in northern Thailand stormed into a neighbor's home, hacked five children to death and inflicted multiple stab wounds on a pregnant woman who was watching them.

Lt. Col. Sombat Kalasuk said the 24-year-old man had a history of mental illness and was living with his family while being treated for depression at a local hospital.

He apparently became agitated by the noise coming from his neighbor's home in a village outside the northern city of Chiang Mai and grabbed a 47-centimeter (19-inch) kitchen knife which he then used to kill the children.

All five children were believed to be under the age of 8. A woman who is 7 months pregnant and was watching the children is being treated for wounds to her face and body.