Police and military in Nigeria's north-eastern Borno State are hunting armed Islamic militants who killed seven people early on Monday.
Police stations were also targeted in January
Some 40 armed men wearing red bandanas and crying "Allahu Akbar" (God is Great) attacked two police stations and made off with looted ammunition.
Earlier this year, militants dubbed the Taleban stormed several police stations in Borno and neighbouring Yobe State.
The group wants to set up an Islamic government in Nigeria.
Three police officers, including a woman constable who was briefly abducted, and seven civilians were killed in the attacks in the towns of Bama and Gworza, 40km (25 miles) apart.
According to the BBC's Mato Adamu in Borno, none of the attackers, who carried a flag with an Islamic symbol during the raid, were apprehended.
After an all-night emergency security meeting in the state capital Maiduguri on Tuesday, Deputy Police Commissioner Aliyu Musa said mobile police units and military reinforcements had been sent to hunt the men down.
Referring to the men as "hoodlums" he said further action would be taken, but he could not divulge further details.
The police spokesman in Abuja, Chris Olakpe, told the BBC that he believed the militiamen had crossed the border from neighbouring Niger.
The attackers burned down the police stations and carried away large amounts of weapons and ammunition, our correspondent says.
He says the raids did not come as a great surprise, because although many "Taleban" - as they are dubbed by local media - were arrested or killed in January, some managed to escape and took their weapons with them.
Borno State spokesman Usman Chiroma told AFP news agency that a vigilante group had battled the Muslim militiamen in Gworza.
He said that one vigilante member had been killed and four more abducted.
The "Taleban" were trapped on a hill outside the town, he said.