Eight people have been killed in religious violence in Nigeria, including a Christian family of seven, while a roadside bomb killed seven others in an area known for Boko Haram activity.
Friday's two incidents follow deadly violence last weekend, which raised fresh questions about the government's strategy to end the bloodshed and a change at the top of the military.
In the first attack, unknown gunmen in cars and on motorbikes burst into the family's house in Unguwar Kajit, a village in the mainly Christian part of Kaduna state, and opened fire, locals said.
"Christian youth provoked by the attack, which they blamed on Fulani Muslims, mobilised and launched reprisal attacks, burning mosques and houses," youth leader Emmanuel Zadiok told AFP.
One person in a mosque died as it went up in flames, said Muslim resident Mohammed Yakub, confirming Zadiok's account.
Kaduna state governor Mukhtar Ramalan Yero has ordered an investigation.
He condemned the attack and "prayed that God should expose the perpetrators", said his spokesman, Ahmed Maiyaki.
In the second incident, seven people were killed and three others seriously injured when their bus ran over a home-made bomb near Kuthra village in the Gwoza area of Borno state, police said.
The Islamist militant group Boko Haram has scaled up deadly attacks in the border area with Cameroon in recent months and Borno state police commissioner Lawan Tanko blamed the group for planting the device.
"The bus was about to pull over to pick some passengers when it rolled over the IED (improvised explosive device) planted by the roadside, causing an explosion," Commisioner Tanko said.
A police bomb disposal unit has been combing the area for further explosives, he added.
Gwoza is some 150 kilometres from the Borno state capital Maiduguri, Boko Haram's spiritual home, where earlier this month a car bomb ripped through a busy market, killing 19.
Boko Haram also attacked military installations in December last year, forcing a city-wide shut-down and raising questions about Nigeria's counter-insurgency strategy.
A state of emergency imposed on Borno and two neighbouring northeast states in May last year has pushed Boko Haram fighters into more remote, rural areas but attacks have continued.
Last Sunday, at least 52 people were killed in Kawuri, some 90 km by road from Gwoza, and 26 died when gunmen stormed a church in Waga Chakawa, in neighbouring Adawama state.
