“We are fine, we are still inside the refinery and we are fighting,” said Brig. Gen. Arras Abdul Qadir, the commander of the troops guarding the refinery, reached by telephone Wednesday afternoon. Asked how long his troops could hold out, he said, “We will see.”

Other accounts from Baiji said the insurgents had total control. A refinery worker reached by telephone who gave only his first name, Mohammad, said that the refinery had been attacked at 4 a.m. and that workers had taken refuge in underground bunkers. An unknown number of natural gas storage tanks were set ablaze. After taking heavy losses, the troops guarding the facility surrendered, at least 70 were taken prisoner and the refinery workers were sent home unharmed, he said.

An Iraqi Army lieutenant from Baiji, also reached by telephone and speaking on the condition of anonymity, said he had fled his unit when it became clear they could not resist the ISIS forces.

Witnesses in the area also reported seeing ISIS checkpoints controlling access to the sprawling refinery area, and smoke rising over the complex from numerous fires.

The attackers had besieged the refinery for the past week, after most of the surrounding Salahuddin Province had fallen under their control.

Foreign workers, including 50 from the German company Siemens, had been evacuated from the refinery, according to news reports quoting Siemens officials. Olive Group, a security company, said it had evacuated its six clients from the refinery in recent days “in a routine road move.”