Heavy gunfire was heard near the presidential palace in Niger's capital Niamey on Wednesday around 4 a.m. (0300GMT), according to reports on the ground.
The shooting lasted about an hour and calm returned around 5 a.m. (0400GMT), with the exception of a few intermittent shots.
While Nigerien authorities did not immediately comment on the incident, local and international media reported an attempted coup, which Anadolu Agency cannot confirm at this time.
The incident comes just days before the inauguration of the newly elected president, Mohamed Bazoum, scheduled for Friday.
Bazoum's victory was contested by his rival Mahamane Ousmane after the second round of elections held on Feb. 21.
Ousmane had called for demonstrations starting yesterday to challenge the results of the election.