Gunfire erupted early on Thursday at the airport in Niger's capital, Niamey, residents told AFP, five months after a terrorist attack at the facility.
Niger has been ruled for the past three years by a military junta that has struggled to contain violence blamed on terrorists.
In January, the Diori Hamani international airport in Niamey and a military drone base were targeted in an attack claimed by the ISIS in the Sahel (EIS).
Nigerien armed forces and their Russian allies repelled the strike, which was a rare development since violence had previously been contained to other parts of the vast Sahel country.
"I heard the first shots around 6 o'clock (0500 GMT). The shooting was coming from the airport entrance," a resident told AFP by telephone on Thursday.
He said firing was still ongoing two hours later.
Another resident confirmed the gunfire was coming from the airport entrance, where there is a security checkpoint.
A number of residents said a large military presence had been put in place at the airport.
Twenty assailants were killed and four soldiers wounded in the surprise assault on January 29, which caused damage, authorities said.
The head of the ruling junta, Abdourahamane Tiani, who seized power in a coup in July 2023, said on state television "a flaw in the system" had "enabled the attack", whose aim, he said, "was to destroy all of the air capabilities" of the army.
In recent weeks, the authorities have started tearing down thousands of illegally built homes next to Niamey airport.
They alleged the shanty towns had been infiltrated by extremists.
The demolitions affected 26,000 people living in four neighborhoods that occupy nearly a quarter of the airport area, authorities said.
The airport perimeter fence has been extended and more than 350 security cameras installed inside and outside the perimeter.
Niger and its military-ruled allies in west Africa -- Burkina Faso and Mali -- have faced a decade of violence attributed to extremists.
They have moved away from former colonial power France and sought support from other partners.
