Nigerian hospital officials say a wave of attacks by suspected Boko Haram militants has left at 23 people dead, while authorities say they have arrested a prominent member of the Islamist sect.

Hospital officials said Saturday the deaths resulted from a series of explosions and shootings that began on Thursday in the northeastern part of the country. Residents said several buildings were destroyed in the region, which has been targeted in previous attacks by the militant group.

Late Friday, Nigerian military officials announced they had arrested a Boko Haram commander at the home of a prominent senator near the city of Maiduguru. They did not name the senator.

Boko Haram has been blamed for the deaths of more than 1,500 people since 2009. Much about the group remains unclear, but the militants are believed to want a strict form of Islamic law applied across the country.

Earlier this month, Human Rights Watch said Boko Haram had committed “widespread and systematic murder and persecution” in attacks on government agents, Christians and moderate Muslims. However the U.S.-based group also said the Nigerian government had engaged in abuses while fighting the militant group.

The rights group called for the International Criminal Court to examine the actions of both sides in the conflict.