Tensions remain high in Nigeria where authorities are searching for members of a radical Islamic sect believed to have carried out a wave of deadly bombings across the north in recent days.

Authorities believe Boko Haram orchestrated the attacks, which have killed at least 100 people since Friday.

Police in the city of Damaturu set up roadblocks Monday to check vehicles for weapons or suspected militants.

The secretary general of the Organization of Islamic Cooperation strongly condemned the violence. Ekmeleddin Ihsanoglu, the leader of the 57-nation bloc, described the bombings as criminal acts contrary to “all human and noble Islamic values.”

The United States embassy in Nigeria has warned the sect plans to strike three hotels and other sites in the capital, Abuja, during the Eid-al-Adha holiday. The locations include sites frequented by diplomats, politicians and foreigners.

Police could be seen in front of those hotels Monday, however security officials played down the threat. National Security Advisor Andrew Azazi said the threat of the attacks is “not news” and the U.S. statement is spreading unnecessary panic.

Attacks carried out since Friday have so far targeted police stations, churches and an army base in small towns across the predominantly Muslim north.

Boko Haram has said it is fighting to establish a strict Islamic state in northern Nigeria. The group, whose name means “Western education is forbidden,” does not recognize Nigeria's government or constitution.

The group has claimed responsibility for the August 26 attack on the United Nations headquarters in Abuja that killed dozens of people.

Nigeria's population of 160 million is divided almost in half between Muslims living mostly in the north and Christians living mostly in the south.