Around 30 gunmen rained bombs and gunfire on a police station in Kano, killing a woman in the latest attack blamed on Islamist group Boko Haram in Nigeria\'s second city of Kano. The country\'s main northern town has lived in fear amid continued chaos since a coordinated wave of attacks after Muslim prayers on Friday killed at least 185 people, in Boko Haram\'s deadliest ever onslaught. The armed group converged on the station late Tuesday from two different directions on motorcycles and in Mercedes cars, witnesses said. The gunmen \"were just telling people to move away, they were just here to do their work. They just opened fire on the police station,\" a resident who requested anonymity told AFP on Wednesday. The station, in Kano\'s densely populated Sheka area, was heavily damaged in the attack: its windows were shattered, the walls were smoke-stained and blood had covered nearly the entire bathroom floor, according to AFP reporters. The holding cells at the back of the station were opened. A purported spokesman for Boko Haram has said last week\'s attacks were in response to a refusal by the authorities to release arrested members of the group from custody. A huge crowd had gathered outside the station on Wednesday, surveying the wreckage after an attack that also injured one policeman, according to witnesses. There was no police in sight, just neighbourhood youths trying to control the crowd. \"A policeman was shot in the leg. A woman who came to see a policeman was shot in the stomach. She died,\" the same resident told AFP, adding that the woman was standing outside the station\'s gate and talking to the officer when she was shot. Multiple residents said the attackers hurled two bombs at the station before opening fire. \"It was around 6:30 pm (1730 GMT) when people were preparing for the evening prayers and a large group of gunmen arrived in the area and opened fire on the police station and threw in bombs,\" one witness said. The US State Department on Tuesday urged Africa\'s most populous nation and top oil producer to \"stand united\" in the face of growing sectarian strife, while a visiting US delegation promised security assistance. Earlier on Tuesday, gunfire erupted when security forces raided a house suspected to be a Boko Haram hideout shortly after midnight. They opened fire and a suspect fired back resulting in a shootout lasting around four-and-half hours, sending residents into panic. According to Human Rights Watch, Boko Haram has killed more than 935 people since the group -- whose name can be loosely translated as \"Western education is sin\" -- launched a violent campaign in July 2009. More than 250 of those deaths have come in 2012 alone. A US delegation led by William Fitzgerald, the deputy assistant secretary of state for African affairs, and Joseph McMillan, the principal deputy assistant secretary for defence, held security talks with Nigeria in the capital Abuja on Tuesday. The two sides agreed to boost the operational capabilities of the Nigeria security services in the face of internal security threats. Boko Haram which has staged a series of increasingly sophisticated and bloody attacks, often targeting security agencies and lately Christians, is believed to have a number of factions with differing aims, including some with political links and a hardcore Islamist cell. President Goodluck Jonathan has vowed to beef up security as he grapples with the worst crises of his nine-month tenure -- a surge in Boko Haram attacks and mounting social discontent.