The U.S. military ramped up evacuations in Afghanistan on Monday, flying out roughly 12,700 people on 37 flights, the largest single day of airlifts out of the country.

In total, approximately 21,600 people were evacuated from Afghanistan during the 24-hour period between early Monday and early Tuesday, a White House official said, including 8,900 people who were transported on 57 coalition flights.

Since Aug. 14, the U.S. has evacuated or facilitated the evacuation of about 58,700 people, the White House said.

The new numbers reflect an improving evacuation operation in Afghanistan, which has been marked by chaos since the Taliban overran the country and took over Kabul just over a week ago.

In comparison, 28 U.S. military flights evacuated 10,400 people the day prior, which was previously the largest single-day airlift since the evacuation began.

The Biden administration is working to evacuate American citizens and Afghans who assisted U.S. forces in Afghanistan as quickly as possible. Biden administration officials say they believe the number of Americans remaining in Afghanistan to be in the thousands but are working to determine a precise number.

The White House has not provided a breakdown of how many of the evacuees are Americans and how many are Afghans.

Meanwhile, Biden faces a decision on whether to extend the planned Aug. 31 withdrawal date so that U.S. forces can remain in the country to continue evacuations.

Biden is under pressure from foreign allies, human rights advocates, veterans groups and some members of Congress to do so. However, such a move would risk conflict with the Taliban, which said the U.S. would be crossing a “red line” if it kept troops in Afghanistan beyond Aug. 31.