MAIDUGURI, Nigeria -- Members of a radical Muslim sect attacked a church in northeast Nigeria during a worship service, part of a series of assaults that killed at least 13 people, authorities said Saturday.

The church shooting came as Boko Haram members attacked a beauty salon and fought government forces Friday night as part of its continuing sectarian battle against Nigeria's weak central government. In the last few days alone, the group has killed at least 44 people, despite the oil-rich nation's president declaring a state of emergency in regions hit by the sect.

In Yola, the capital of Adamawa state, gunmen covered their faces with black cloth when they attacked Apostolic Church, local police commissioner Ade Shinaba said. Shinaba said at least eight worshippers died in that attack.

At a nearby beauty salon, at least three others were killed in a similar attack.

"Three gunmen with their faces covered with black cloth burst into my salon and started shooting at customers, chanting, 'God is great, God is great,'" said Stephen Tizhe, 35.

In the town of Potiskum in Yobe state, gunmen set two banks ablaze with gasoline bombs, starting a gunfight with police that lasted three hours, local police commissioner Tanko Lawan said. At least two people were killed in the fight, he said.

No arrests have been made in either attack, authorities said.

The attacks Friday night came after gunmen claimed by Boko Haram attacked a town hall earlier that day in Mubi, Adamawa state, killing at least 20 people who had gathered for a meeting of the Christian Igbo ethnic group. On Thursday night, the sect also attacked a church in Gombe state, killing at least eight people.

In a statement Friday to The Daily Trust, the newspaper of record in Nigeria's north, a Boko Haram spokesman using the nom de guerre Abul-Qaqa claimed responsibility for the attacks in Gombe and Mubi.

"We want to prove to the federal government of Nigeria that we can always change our tactics," the spokesman said.

Boko Haram, whose name means "Western education is sacrilege" in the local Hausa language, is responsible for at least 510 killings last year alone, according to an Associated Press count. It has targeted churches in the past in its campaign to implement strict Shariah law across Nigeria.

The group claimed responsibility for attacks that killed at least 42 people in a Christmas Day strikes that included the bombing of a Catholic church near Abuja. The group also claimed an August suicide car bombing that targeted the U.N. headquarters in the capital, killing 25 people and wounding more than 100.

Nigeria's central government has been slow to respond to the sect. On Dec. 31, President Goodluck Jonathan declared regions of Borno, Niger, Plateau and Yobe states to be under a state of emergency, meaning authorities can make arrests without proof and conduct searches without warrants. He also ordered international borders near Borno and Yobe state to be closed.

However, the areas where the recent church and town hall attacks happened are not in the areas marked by the president.