Six children and a teacher were wounded when assailants threw a homemade bomb at an Islamic school in a predominantly Christian area, police in Nigeria said Wednesday.
The attack took place in the city of Sapele, as about 50 children were gathered for an Arabic class.
Delta State police spokesman Charles Muka said that the attackers drove by a school and threw homemade explosives into a classroom Tuesday morning.
The wounded children were all aged younger than nine, Reuters reported. At least one was aged four.
Investigators suspect a local vigilante group was behind the incident, Muka added.
The latest incident follows coordinated attacks by radical Islamist militants on Christmas Day, which killed at least 39 people.
Analysts say the attacks risk reviving sectarian violence between the mostly Muslim north and Christian south, which has claimed thousands of lives in the past decade.
The radical Muslim sect known as Boko Haram has claimed responsbility for the church attacks. Boko Haram aims to impose Islamic Shariah law across Nigeria.
Many northern Nigerian Christians fear the Christmas Day bombings could lead to a religious war in Africa's most populous country.
Meanwhile, a family of four was killed in a machete attack on Wednesday in Nigeria's ethnically and religiously mixed Plateau state — on the threshold of the country's largely Muslim north and its mostly Christian south.
There was no immediate suggestion the killings had any link to Sunday's church bombings.