With hours left to evacuate Afghanistan, the US is racing to get remaining troops, American citizens, and allies out of Kabul

• The US has just hours left before the Afghanistan evacuations deadline at 11:59 p.m. local time on August 31.
• The race is on to get remaining US troops, citizens, and allies out of the Taliban-controlled country.
• It's unclear how many US troops or Afghan allies are in Kabul. Around 300 US citizens are still there.

The US has just hours left before its Afghanistan evacuation mission wraps up by President Joe Biden's August 31 deadline.

And as the clock ticks, the US is racing to get the remaining American troops, citizens, and allies out of the now Taliban-controlled country even as more terror threats loom.

The deadline for all US troops and diplomats to be out of Afghanistan is Tuesday at 3:29 p.m. ET (11:59 p.m. local time), US defense officials told Fox News.

At this point, it is unclear exactly how many US service members or Afghan allies remain in Afghanistan ahead of Tuesday's deadline and officials have been deliberately vague on the figures due to safety reasons.

A US official told Reuters in a report published Saturday that there were fewer than 4,000 troops left at the Kabul airport, where ongoing evacuation efforts are being carried out.

Pentagon spokesman John Kirby confirmed to reporters at a press briefing that the final withdrawal of troops had started, but he declined to reveal how many service members remained in Kabul.

US Secretary of State Antony Blinken told ABC's "This Week" on Sunday, "We have about 300 American citizens left [in Afghanistan] who have indicated to us that they want to leave."

"We are very actively working to help them get to the airport, get on a plane, and get out of Afghanistan," Blinken said.

In the last days of the evacuation, the US is focused on getting US troops and equipment out of Kabul, but Kirby suggested during a Monday press briefing that they can still evacuate American citizens and Afghan allies while they get US troops out.

The New York Times reported Sunday that hundreds of students and families from American University of Afghanistan were told that the US wasn't doing any more civilian evacuation flights, partly because the security threat at the airport was so high.

Biden warned Saturday that another terrorist attack at the Kabul airport - where an ISIS-K suicide bombing killed 13 American troops and more than 160 Afghans on Thursday - "is highly likely in the next 24-36 hours."

"This is the most dangerous time in an already extraordinarily dangerous mission, these last couple of days," Blinken told ABC News. "And so we will do everything possible to keep people safe, but the risk is very high."

Kabul's Hamid Karzai International Airport was the target of a rocket attack Monday as the US continued evacuations. The US missile defense system intercepted the rockets and there were no immediate reports of US casualties.

Biden was briefed on the attack, the White House said in a statement, adding, "The President was informed that operations continue uninterrupted at HKIA, and has reconfirmed his order that commanders redouble their efforts to prioritize doing whatever is necessary to protect our forces on the ground."

Meanwhile, since evacuation operations started on August 14, 122,000 people - 5,400 of whom were Americans - were airlifted out of Afghanistan, Army Maj. Gen. William Taylor said at a briefing Monday.

Taylor said 1,200 people were evacuated within the last 24 hours.