United States Department of Defense, on Monday, said that the last plane carrying Americans has left from war-torn Afghanistan, ending a stretched evacuation effort and concluding the two-decade-long war, according to US media reports.

Minutes before the announcement was made by the Pentagon on Monday, personnel connected to the Taliban said that as the plane departed Afghanistan, celebratory gunfire was heard. 

General Frank McKenzie, head of US Central Command said in an announcement on Monday that the planes took off from Kabul airport at 3:29 pm EDT, or one minute before midnight in Kabul, according to reports from Associated Press.

"Tonight's withdrawal signifies both the end of the military component of the evacuation, but also the end of the nearly 20-year mission that began in Afghanistan shortly after September 11, 2001", McKenzie said.

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According to reports from AFP, the United States Commander and Ambassador present in Afghanistan's Kabul were the last to board the evacuation flights.

General McKenzie said that some American citizens who wanted to leave Afghanistan remain in the country after US departure, according to reports from Associated Press.

In the announcement, the Pentagon spokesperson admitted that the United States military could not evacuate as many Afghans it initially hoped.

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With the departure of the last of its troops, the US ends its 20-year war with the Taliban back in power. Many Afghans remain fearful of them or further instability, and there have been sporadic reports of killings and other abuses in areas under Taliban control despite pledges to restore peace and security.

Hours before the last plane flew off from Kabul on Monday, the Islamic State fired a series of rockets at the Hamid Karzai International Airport in Kabul. However, the attempt was reportedly a failed one as no lives were harmed in the attack and the United States' military and cargo planes continued their operations.