Officials say suspected Islamic militants killed 20 people including a traditional ruler in northeast Nigeria in four attacks across the country in three days.
Monday's massive explosion killed 175 people in Abuja, the capital, and yesterday gunmen kidnapped about 100 female students in the northeast.
Politician Hyeldi Bwala says gunmen marched into the palace of the emir of Gwoza yesterday evening and gunned him down along with his security guard.
Just last week the emir had appealed to the government to "save our souls," saying his people were being attacked daily.
Two officials say gunmen this morning attacked a village in Gwoza district and killed 18 people.
The attacks strengthen doubts about the ability of Nigeria's military to contain the 5-year-old Islamic uprising.