Several people were sent to a hospital in the northeast Nigerian city of Maiduguri after being injured when jihadists on thursday allegedly fired rockets onto the city, killing at least four people.
According to emergency services, several other people were injured in three neighbourhoods: Gomari, Bulunkutu and Ajillari-Kuros.
"Five rockets fell on the town this morning but it is too early to give details of the destruction and casualties," said Umar Ari, an anti-jihadist militiaman.
The Borno state capital was at the time preparing for an official visit by President Buhari, who arrived in the city at around 12pm GMT.
Residents blamed the attack on the Islamic State in West Africa, which is active in the region.
"We evacuated four bodies to hospital from a house hit by one of the rockets," an emergency services official said on condition of anonymity.
In Maiduguri, president Buhari was expected to inaugurate several projects including a flyover and an education centre at the city's university.
In the past, ISWAP and its rival Boko Haram launched deadly rocket attacks on Maiduguri during the jihadist insurgency that killed more than 40,000 people and displaced nearly two million.
In early December, the jihadist fired two rockets into the city, hitting two houses in Gomari and Bulunkutu but this time without causing any casualties, according to residents.
In February, at least 17 people were killed and about 40 injured in a dawn rocket attack on Maiduguri by ISWAP fighters.
ISWAP consolidated its control in the northeast after the death of the Boko Haram leader in May in clashes between the two groups.