Photo Credit: Rahmat Gul / Associated Press

The U.S. government sent a notice to Americans trying to escape Afghanistan after a rapid takeover by the Taliban over the weekend, telling them to make their way to the airport in Kabul, but that it could not guarantee their security on the way there.

A congressional aide told CBS News there were no partners left in Afghanistan to safely get the 10- to 15,000 Americans trapped around the country to the capital of Kabul.

Instead, a note went out to American citizens requesting to be evacuated from Afghanistan that said:

To American Citizens,

Thank you for registering your request to be evacuated from Afghanistan.   The U.S. Embassy in Afghanistan has confirmed that an undefined number of U.S. government-provided flights will begin soon. Please make your way to Hamid Karzai International Airport at this time.

It said in bold and capitalized letters:

According to White House press secretary Jen Psaki on Tuesday, there are more than 11,000 American citizens trapped in the country. However, this was “self-identifying” Americans only.

Former George W. Bush administration official Robert Charles said there could be as many as 40,000 Americans stuck in the country.

The Pentagon said in the last 24 hours that 165 Americans were flown out, with flights consisting of a total of 700 to 800 passengers.