Nigeria was on high alert Monday after the United States warned of fresh attacks following a wave of deadly blasts claimed by Islamists killed 150 people in the northeast of the country. Friday\'s attacks in the city of Damaturu were among the deadliest ever carried out by Boko Haram, an Islamist sect based in the north of Africa\'s most populous country. The US embassy in Nigeria warned the sect could next strike hotels and other targets in the capital Abuja during the Muslim holiday of Eid al-Adha. \"Following the recent Boko Haram, aka Nigerian Taliban, attacks in Borno and Yobe State, the US embassy has received information that Boko Haram may plan to attack several locations and hotels in Abuja,\" the embassy said in a statement. Security was stepped up in Abuja, which has been a target of past attacks, including an August 26 suicide bomb at the UN headquarters which claimed 24 lives. The US embassy said potential targets could include the Nicon Luxury, the Sheraton and the Transcorp Hilton, Abuja\'s premier hotels. Embassy staff had been told to avoid the venues. Some 13,000 policemen and specialist anti-terror squads were deployed to mosques and churches and other strategic locations across the city on Sunday, a police official said. Worshippers were screened by metal detectors before they entered some churches. In the grief-stricken city of Damaturu where the 150 died, thousands of Muslims gathered for Eid el-Adha, or the Feast of Sacrifices prayers at an open ground patrolled by dozens of armed police. President Goodluck Jonathan, who described the wave of gun and bomb attacks in the capital of Yobe state as \"heinous\", appealed to Muslims to pray for peace as they marked Eid. \"It is a period that we are all expected to live in peace but as a nation we have our own challenges, even during this holy period we still have incidents happening here and there,\" he said. While churches and police were among the initial targets, gunmen fired indiscriminately in the streets. Muslims and Christians alike were among those killed. \"The death toll cuts across religion, profession, status,\" said Ibrahim Farinloye, a spokesman for Nigeria\'s emergency management agency. \"The attack seems to have been haphazardly carried out which explains the heavy toll. Both Muslims, Christians, civilians, soldiers, policemen and other paramilitary personnel were all part of the casualties.\" Eid celebrations in the sleepy and dusty city of Damaturu were low key on Sunday. Gudusu, 58, who lost a brother in the attacks, voiced outrage at Boko Haram, sobbing as prayers were offered for the sibling he buried on Saturday. His family called off the celebrations but simply prayed and slaughtered a ram to mark Eid al-Adha, one of the most important feasts in the Muslim calendar. \"People are struggling to strike a balance between the merriment of the season and the losses the city has incurred from the attacks, especially the large number of people that have been killed,\" said another resident Aisami Bundi. Pope Benedict XVI appealed for an end to the violence, saying it did \"not resolve problems but increases them, sowing hatred and divisions.\" Boko Haram claimed Friday\'s rampage and warned of more attacks. Opposition Action Congress party of Nigeria said it was \"horrified\" at the scale of the attacks alleging \"government has now run out of ideas on how to tackle this crisis.\" Militants from Boko Haram, whose name means \"Western Education Is Sin\" in the regional Hausa language, have in the past targeted police and military, community and religious leaders, as well as politicians. The sect, which wants to see the establishment of an Islamic state in northern Nigeria, staged an uprising which was brutally put down by security forces in 2009. Nigeria\'s more than 160 million people are divided almost in half between Muslims and Christians, living roughly in the north and south of the country respectively.