The attack occurred as Bayero left a ceremony to launch an Islamic school at Mussalaci Murtala, Nigeria's Channels TV reported.
The gunmen killed Bayero's driver, an orderly and a traditional guard, who tried to protect Bayero. The identities of the other dead were not reported.
Bayero was unharmed and taken to an undisclosed location for safety, The Daily Trust, Abuja, Lagos, reported.
Bayero's two sons were injured and taken to a nearby hospital for treatment.
At least seven injured were taken to Aminu Kano Teaching Hospital and five injured were taken to Murtala Muhammad Specialist Hospital, officials said.