About 170 civilians boarded the flight after a Qatari convoy escorted them to the airport in Kabul, Afghanistan, Reuters reported, citing a Qatari official. Passengers also included Afghans as well as nationals from United Kingdom, Germany, Italy, Belgium, the Netherlands and Croatia.
Khalilzad said he was "grateful that more Americans were able to leave today on a Qatar Airways flight."
"As President Biden said, there is no deadline for Americans remaining in Afghanistan," the envoy added. "We remain committed to get them out if they want to come home."
The exact number of Americans on board the flight was not immediately clear. The State Department did not immediately return a request for comment.
The passengers will reportedly be housed in a compound in Doha, Qatar, before being transported to their home nations.
Chartered flights resumed on a limited basis following the chaotic U.S. withdrawal from Afghanistan, though reports emerged that the Taliban was hindering planes from leaving the country.
During a Sept. 8 press conference, Secretary of State Antony Blinken said U.S. officials had "made clear" to the Taliban that flights should be allowed to depart.
"Those flights need to be able to leave, and the United States government, State Department – we are doing everything we can to help make that happen," Blinken said. "Those flights need to move. I pointed out some of the complications that are there, but those flights need to move."
The Biden administration has pledged an open-ended commitment to stranded Americans who wish to leave Afghanistan in the future. Blinken and other top officials have warned of consequences if the Taliban does not allow safe passage out of the country.