KABUL, Aug. 28 (Reuters) -- US forces helping evacuate Afghans desperate to flee Taliban rule were on alert for more attacks on Friday (Aug 27) after an Islamic State suicide bombing outside Kabul airport killed at least 92 people, including 13 US service members.

The White House said the next few days of an ongoing US evacuation operation that the Pentagon said has taken about 111,000 people out of Afghanistan in the past two weeks are likely to be the most dangerous.

Pentagon spokesman John Kirby said the United States believes there are still "specific, credible" threats against the airport after the bombing at one of its gates.

"We certainly are prepared and would expect future attempts," Kirby told reporters in Washington. "We're monitoring these threats, very, very specifically, virtually in real time."

Earlier in the day US officials said a total of approximately 5,100 Americans had been evacuated, with about 500 more waiting to leave.