(MARAWI, Philippines) — Army tanks packed with soldiers rolled into a southern Philippine city Thursday as gunfire and explosions rang out after militants linked to the Islamic State group torched buildings, seized more than a dozen Catholic hostages and raised the black flag of ISIS. At least 21 people have died in fighting that erupted late Tuesday, when the army raided the Marawi hideout of Isnilon Hapilon, who is on Washington’s list of most-wanted terrorists and has a $5 million bounty on his head. The operation went wrong as the militants called in reinforcements and swept through the mostly Muslim city of 200,000 people.