In one of the largest airlift operations in history, Ramstein, Germany, has become the central hub to evacuate and process Afghan evacuees. According to the U.S. Air Force, the vast majority of people fleeing Afghanistan will come through Ramstein, and the base has already received at least 15,000 people as of this morning.

Upon arrival to Ramstein, refugees are immediately given medical aid, food and shelter while they undergo a final security check. Air Force officials say the goal is to get people in and out as quickly as possible, and aim to have people on their way to America within three days.

According to an internal report obtained by ABC News on Monday, officials estimate that some 20% of evacuees at Ramstein lacked documentation.

Top U.S. general in Europe Tod Wolters spoke with Pentagon reporters Wednesday and said that overall European bases could potentially process as many as 25,000 evacuees.

“We’ve received 55 flights at Ramstein Air Base, Germany, and we currently have 5783 evacuees on deck at Ramstein. We’ve received three flights at Naval Air Station Sigonella,” said Wolters on Wednesday.

The makeshift tent camp in Ramstein has the capacity to hold 10,000 evacuees, and 7,000 refugees have already been processed, according to Walters.

But, some are concerned that the increasing number of evacuees will overwhelm resources and facilities at the Ramstein base in coming days.

In addition to Ramstein, Germany has also agreed to let the U.S. use the nearby U.S. Army garrison in Kaiserslautern and a joint training facility in Grafenwoehr in eastern Germany to house evacuees, ABC News reported on Monday.