Four children were murdered by their parents over the weekend in the Dominican Republic, police said Monday in the Caribbean country, which has suffered a spate of such killings.

A 36-year-old woman living on the outskirts of the capital Santa Domingo killed her three children aged 7, 9 and 11 by poisoning their fruit juice on Sunday before taking her own life by ingesting the liquid, police said.

Officers found a handwritten note at the scene believed to have been left by the woman but have not disclosed the contents.

On the same day in the capital, a man was arrested on suspicion of suffocating his toddler son, aged 1 year and 8 months.

At least two other cases of suspected filicide — when a parent intentionally kills their child — have been reported on the island of nearly 11 million inhabitants so far this month.

A couple was arrested last week in the capital, accused of causing the death of a 7-year-old girl in their care, who showed “signs of physical abuse and barbarity,” according to authorities.

Days earlier, on August 11, a man allegedly hanged his 2-year-old son and then took his own life in the northeastern city of Nagua.

According to a paper published in the National Library of Medicine, 90% of filicide cases worldwide involve biological parents and 10% involve stepparents.

In the United States, roughly 2.5% of all homicide arrests were for parents who killed their children, according to a 2014 analysis, which amounts to an average of about 500 filicide arrests each year. Filicides are believed to account for roughly two-thirds of fatal child abuse cases, according to the analysis.