KANO CITY, Nigeria (CNN) -- Police said a group of suspected militants attacked a police station in Nigeria's Kano province on Friday. Military forces have since cordoned off the area around the provincial capital city of Kano where the attack apparently occurred, according to witnesses. Gunfire and tracer rounds could be heard and seen during the incident, according to CNN personnel in the area. The attack appears to have ended, and its not clear if there were casualties. Earlier, gunmen shot and killed at least 16 people and burned their bodies in the northwestern state of Zamfara, according to an official who asked not to be named, citing security concerns. The incident occurred Thursday when about 100 armed men blocked a nearby highway, delaying vehicle traffic and taking hostages in the area, a restive region that borders Niger. Some of the hostages stormed the gunmen, resulting in a deadly shootout, the official said. It is not clear whether the men were robbers or the incident was a reprisal attack over discord in the region, but it comes immediately following a separate attack against a state official in the same area. "We are quite confused about a lot of things these days, the police may say it is not (the militant group) Boko Haram, but even they are not sure because they have not arrested anyone in all these attacks in the last 36 hours," said attorney Barrister Labaran in the provincial capital of Gusau. Earlier this week, the country's inspector general of police was fired amid a rash of violence across Nigeria. One day last week, at least 180 people were killed in the city of Kano -- an attack linked to Boko Haram, an Islamist militant group that has carried out multiple bombings and shootings across the north.