In fierce fighting Sunday, Nigerian troops clashed with Islamic extremists who attacked Maiduguri, the biggest city in northeast Nigeria. Dozens of combatants have been killed and wounded, soldiers and hospital workers said.
“Coordinated air and land operations are being conducted now,” Defense Ministry spokesman Brig. Gen. Chris Olukolade said in a message posted on Twitter.
Troops blocked roads leading into the city, which also is preventing civilians from escaping.
“We believe hundreds of thousands of civilians are now at grave risk,” Amnesty International said.
The attacks come the day U.S. Secretary of State John Kerry is expected in Lagos, Nigeria’s commercial capital nearly 1,000 miles (more than 1,500 kilometers) southwest of Maiduguri.