Hundreds of residents of a northeastern Nigerian city were fleeing Sunday after three days of Islamist attacks that left at least 31 dead and many buildings and properties razed, witnesses said.The troubled city of Potiskum had been under security lockdown since Thursday with troops patrolling the streets and residents keeping in-doors for fear of new attacks.Security was relaxed Sunday morning and hundreds of residents took advantage to flee the restive city."A lot of people are leaving the city following the relaxing of the lockdown on the city by soldiers this morning,” said a resident who gave his name as Hassan."Hundreds of residents, especially those living on the outskirts of the city, which have been worst hit by the attacks, are fleeing with their belongings,” he said."Those of them with personal cars are stuffing personal belongings into their vehicles and heading out of the city, while others are taking buses and taxis at the garage and along the main road, heading south,” he said.Hassan said he was already thinking of abandoning the embattled city in the coming days.A fleeing resident, Hamisu Nababa, said he was leaving with his entire family."My wife and three children are in trauma from the attacks and want a change of environment where they can have peace,” he said, adding they were heading to Kaduna, some 600 kilometres (350 miles) to the west, to stay with a relation."Many people are leaving now that the military has opened the road and allowed people to move in and out of the city,” he added.Potiskum, the commercial hub of Yobe state, has been hard hit by near daily attacks by Boko Haram Islamists in recent weeks, prompting heavy deployment of troops and armoured vehicles to forestall fresh violence."Soldiers have tightened security in the city with several checkpoints mounted every few hundred metres all over the city,” resident Bukar Kolo told AFP."Vehicles are thoroughly searched and passengers frisked at every checkpoint. Pedestrians passing by checkpoints have to raise their hands to be sure they are not concealing weapons,” he said.He said most churches were closed as worshippers kept away for fear of attack."Christian residents stayed home for safety reasons. A church was also burnt in the attack and people are afraid to go for Sunday church service for fear of possible attack,” he said.A wave of attacks by suspected Islamists which began on Thursday left at least 31 people dead and several buildings destroyed.Residents said the toll could be higher as some relations had taken some bodies from the streets for burial.Boko Haram’s insurgency in northern and central Nigeria and the state’s military response are believed to have left more than 2,800 people dead since 2009.Boko Haram has claimed to be seeking an Islamic state in Nigeria, though its demands have repeatedly shifted.Nigeria, Africa’s most populous nation and largest oil producer, is divided between a mainly Muslim north and predominantly Christian south.