Business Insider reports that Afghan government troops surrendered the Bagram airbase housing Pul-e-Charki prison, which has around 5,000 prisoners to the Taliban on Sunday.
Thousands of inmates, including members of the Islamic State and al-Qaeda, were released from a prison on the outskirts of Kabul as the Taliban called for a "peaceful transition" of power.
Business Insider reports that Afghan government troops surrendered the Bagram airbase housing Pul-e-Charki prison, which has around 5,000 prisoners to the Taliban on Sunday.
Footage published by an Afghan news agency, which supports the Taliban, appears to show militants letting the inmates out.
Local residents say they have also heard gunfire coming from the facility, the BBC reported.
The Taliban arrived on the outskirts of Kabul on Sunday, several days after capturing other major cities in the country.
The Taliban militants, who have now taken over the government, also declared the war over a day after seizing the capital, while Western nations scrambled to evacuate their citizens from an increasingly chaotic Kabul airport.
President Ashraf Ghani fled the country on Sunday as the Islamists entered Kabul virtually unopposed.
According to him, he decided to flee to prevent bloodshed.
"Today is a great day for the Afghan people and the mujahideen. They have witnessed the fruits of their efforts and their sacrifices for 20 years," Mohammad Naeem, the spokesman for the Taliban's political office, told Al Jazeera TV.
"Thanks to God, the war is over in the country."
It took the Taliban just over a week to seize control of the country after a lightning sweep that ended in Kabul as government forces, trained for years and equipped by the United States and others at a cost of billions of dollars, melted away.
Al Jazeera broadcast footage of what it said were Taliban commanders in the presidential palace with dozens of armed fighters.
Naeem said the form of the new regime in Afghanistan would be made clear soon, adding the Taliban did not want to live in isolation and would call for peaceful international relations.
"We have reached what we were seeking, which is the freedom of our country and the independence of our people," he said. "We will not allow anyone to use our lands to target anyone, and we do not want to harm others."