setting up alternate routes to the airport because of those threats. >> reporter: one of four afghan soldiers wounded in a fire fight after an unknown sniper killed a comrade who was guarding kabul's airport. the attack followed warnings that isis posed a threat to the evacuation of thousands of foreigners and afghans from the capital. >> the threat is real, it is acute, it is persistent, and it is something that we are focused on with every tool in our arsenal. >> reporter: this was the first recent attack on the airport, and it came as the state department said that afghans who've been issued special immigration visas would no longer be allowed into the airport. thousands of others already inside are being evacuated. this is the ultimate stage for evacuees before they get on an aircraft and get out of the country to safety. they're down to about the last 10,000, having moved 10,500 the last 24 hours. but the thousands of people left