Residents in a south-central Nigeria town are under a dusk-to-dawn curfew after separate attacks at a church and mosque this week killed at least 22 people.
The sectarian violence took place in the city of Okene in Kogi State.
On Monday, unidentified gunmen killed 19 people at a Christian church during a worship service. Late Tuesday, armed men killed two soldiers on patrol outside the city's central mosque. At least one other person was killed.
No one has claimed responsibility for the attacks.
Okene is located about 280 kilometers southwest of the capital, Abuja, where U.S. Secretary of State Hillary Clinton is expected to travel on Thursday.
Human Right Watch is calling on Clinton to urge President Goodluck Jonathan to do more to quell the rising violence.
The rights group and government officials have blamed most of the violence on the Islamist militant group known as Boko Haram.
The U.S. government has designated three Boko Haram leaders as terrorists.
Human Rights Watch also urged Clinton to speak with Nigerian leaders about abuses by security forces, corruption and a lack of accountability.
Nigeria is Africa's most populous nation with about 160 million people. It is divided roughly in half between Muslims, who live mainly in the north and Christians, mostly living in the south.
Boko Haram does recognize the Nigerian government or constitution and says it wants to establish a strict Islamic state in the north.