Senior US officials stated on Saturday that the US has evacuated 2,500 Americans from Kabul in the last week, and that the US is battling “time and space” to get people out of Afghanistan.

Major General William Taylor told reporters at the Pentagon that 17,000 individuals had been evacuated so far, including the 2,500 Americans. John Kirby, a Pentagon spokesman, said he didn’t have a “precise count” on how many Americans are still in Kabul and Afghanistan.

“We’re fighting against both time and space,” Kirby said. “That’s the race that we’re in right now. And we’re trying to do this as quickly and safely as possible.”

Kirby declined to describe the specific “threat dynamics” in Kabul but called the security situation “fluid and dynamic.” Kirby said the U.S. goal is to “get as many people out as we can as fast as we can. And so that’s what the focus is.”

Taylor, with the U.S. military’s Joint Staff, said that 3,800 people were evacuated on U.S. military and chartered flights from the Kabul airport in the past 24 hours.

A week after the Islamist militant group Taliban took control of Afghanistan, the United States is desperately trying to evacuate thousands of people including Americans and at-risk Afghans who worked with the U.S.-led forces during America’s two decade-long war in the country. There have been chaotic scenes at the Kabul airport as the evacuation has unfolded.