POTISKUM, Nigeria (AP) — A teenage suicide bomber blew herself up and killed seven other people Saturday outside a bustling bus station in the northeast Nigerian town of Damaturu, the state medical director said of the latest in a string of attacks this week by Nigeria’s home-grown Boko Haram extremists.

Thirty-three people were seriously injured and are being treated at the hospital, said Yobe state’s medical director Garba Musa Fika. Seven are in critical condition and could die if they are not moved to specialist hospitals, according to a nurse who spoke on condition of anonymity because he is not allowed to speak to reporters.

Most victims are women and children among hawkers who sell smoked fish and packets of water at the exit gate to Damaturu Central Motor Park, he said.

The attack comes two weeks after Nigeria’s military said it destroyed about 20 insurgent camps and freed some 700 kidnapped women and children in the Sambisa Forest, where they said the main insurgent fighting force was trapped.

But hundreds of militants tried to attack the biggest military base in northeastern Nigeria on Wednesday night but were repelled by troops at Giwa Barracks in Maiduguri, capital of Borno state and the most populous city in the northeast.

On Friday, Boko Haram seized back the border town of Marte, officials said.

Maiduguri is some 200 kilometers (125 miles) northwest of the nearest reaches of the Sambisa Forest and Marte is even further north.

A week ago, a gunman and suicide bomber attacked a business school in Potiskum, near Damaturu, killing a student and leaving many injured.

A multinational offensive by Nigeria and its neighbors has driven the extremists from all northeastern towns in a 14-week-long offensive. But the Nigerians appear to have bogged down in the Sambisa Forest, where Boko Haram has laid land mines and booby traps.

Thousands have died in the nearly 6-year-old Islamic uprising, about 10,000 last year alone, and more than 1.5 million people have been driven from their homes, some across borders.

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Umar reported from Maiduguri, Nigeria and Associated Press writer Michelle Faul contributed from Lagos, Nigeria.