Fighters from the Nigerian armed group Boko Haram launched an attack Monday on a military base in the northwest Cameroonian city of Kolofata, police say.
"As soon as people heard the first gunfire they fled the city," a police source told the Agence France-Presse news agency. "The gunfire was very heavy."
The attack comes a day after blasts struck an open market selling mobile handsets in the town of Potiskum, in Yobe state, one of three Nigerian states after Adamawa and Borno that have been hit by Boko Haram, which wants to revive a medieval caliphate in Nigeria.
At least six people were killed in Sunday’s blasts after two suspected children strapped with explosives blew themselves up in the open market, witnesses said.
Boko Haram is also suspected of using a 10-year-old girl to detonate a bomb at a market in Maiduguri on Saturday, killing at least 10 people and seriously injuring others. The bomb exploded after explosives were found under the girl's clothing during a search, according to witness accounts.
Maiduguri, the capital of Borno state, lies in the heartland of the Boko Haram insurgency and is often hit by bomb attacks.
Meanwhile, survivors of a separate Boko Haram assault that may have killed up to 2,000 people described days of relentless violence in which, one witness said, some people were slaughtered "like insects."
The accounts, reported by Nigeria's Premium Times newspaper, were given by villagers who fled the carnage in and around Baga, a town in Borno state that lies in the northeastern corner of Nigeria near the border with Chad. The killing unfolded over several days after Boko Haram fighters seized a key military base there on Jan. 3.
Yahaya Takakumi, a 55-year-old farmer, told the Premium Times that he escaped from Baga with one of his wives and spent four days traveling to safety through the bush, but does not know the whereabouts of four of his children, his second wife and his elder brother, a blacksmith in Baga.
"We saw dead bodies, especially on the islands of Lake Chad where fishermen had settled," the newspaper quoted Takakumi as saying. "Several persons were killed there like insects."
Another survivor, Ibrahim Gambo, told the newspaper that he did not know what happened to his wife and daughter. The 25-year-old truck driver said he was part of a civilian militia that initially fought Boko Haram gunmen but was eventually overpowered after promised help from the military did not arrive.
"We came across many dead bodies, some in groups and others by themselves in the bush," Gambo said. "I saw dead children and women, and even a pregnant woman with her stomach slit open."
Amnesty International has described the killing at Baga as possibly the deadliest attack in the history of Boko Haram, which was founded more than a decade ago.
The Nigerian military said in a statement that 14 soldiers were killed and 30 were wounded in the Baga attack, and that it was making a plan to restore "law, order and normalcy" to the area.
Al Jazeera with wire services