At least 17 police officers were killed in Nigeria’s northeast Yobe state after suspected Islamist militants attacked ​a specialised military school that also trains police officers, ‌the national police spokesman said late on Saturday.

Nigeria has been battling an Islamist insurgency in its northeast for over 18 years.

In a different area of ​the northeast, the Lake Chad Basin, the second in command ​of ISIS globally, was killed in an operation conducted by US and Nigerian forces early on Saturday, US President Donald ​Trump and his Nigerian counterpart Bola Ahmed Tinubu said.

The 17 police ​officers were killed on Friday during an attack on the Nigerian Army Special Forces School at Buni Yadi in Yobe state, police spokesman Anthony Okon Placid ​said in a statement.

“The officers, who were undergoing specialised operational ​training at the institution, lost their lives when the militants launched a coordinated ‌attack on the facility from multiple directions,” Placid said.

He said several soldiers were also killed, though he did not give a figure for military casualties.

The Nigerian military did not immediately respond to a request ​for comment.

The violence ​in Nigeria’s northeast began with Boko Haram’s uprising in 2009. The militant group later splintered, giving rise to the ​offshoot the Islamic State West Africa Province, which has ​intensified ⁠attacks on military bases and security personnel.

Abu-Bilal al-Minuki, whose killing in a joint US-Nigerian operation was confirmed by Trump and Tinubu, was a senior ​commander of ISWAP.

The Nigerian government has established ​specialised military institutions, such as the training school that was attacked, to try to ​tackle the terrorist threat.