• Aircraft were warned that Afghanistan air traffic control was handed over to the military and that airspace is uncontrolled.
• United, British Airways and Singapore Airlines are among the airlines that have rerouted their flights.
• The Taliban takeover comes after the almost full exodus of U.S. and coalition forces.

Several airlines are rerouting their flights to avoid Afghanistan airspace after Taliban fighters sealed their takeover of the country, and U.S. and Western officials scrambled to evacuate their personnel.

Afghanistan aviation officials said air traffic control was handed over to the military, and that planes will be "flying in un-controlled airspace at their own risk," according to a notice to pilots.

United Airlines on Sunday started rerouting its U.S.-India flights around Afghanistan.

"Due to the dynamic nature of the situation we have begun routing affected flights around Afghanistan airspace," the airline said in a statement. The carrier serves Delhi from its Newark Liberty International Airport hub daily and five times a week from Chicago O'Hare International Airport. It also flies from Newark to Mumbai daily. The flights are among its longest routes.

British Airways, Virgin Atlantic, Singapore Airlines and Lufthansa also said their flights are avoiding Afghanistan airspace.

United said it "will continue to work closely" with the Federal Aviation Administration and the International Air Transport Association "to evaluate the situation and determine how we continue service to markets impacted."

United is the only major U.S. passenger airline currently flying nonstop to India.

The FAA on July 25 prohibited U.S. airlines from overflying Afghanistan air space below 26,000 feet, which is lower than cruising altitude for such long flights, "due to the risk posed by extremist/militant activity and limited risk mitigation capabilities."

A United spokeswoman said the decision to route around Afghanistan on Sunday was its own.

Flydubai and Emirates airlines said they suspended flights to Kabul.

"Customers holding tickets with final destination to Kabul will not be accepted for travel at their point of origin," Emirates said, directing customers to reach out to the carrier or travel agents.

Earlier Sunday, Emirates Flight EK640, a Boeing 777-300, returned to Dubai after nearing Kabul. The U.S. Embassy in Kabul warned of reports of fire at the airport.

The U.S. State Department late Sunday said it was working to secure Kabul's Hamid Karzai International Airport to evacuate U.S. personnel, local employees, their families and "other particularly vulnerable Afghan nationals" from the country using civilian and military flights.

Thousands of Afghans desperately trying to flee the country swarmed the airport.