(CNN) -- A bomb blast Monday killed eight people and injured at least 12 others at a medical school in Kano, Nigeria, the city's police commissioner said.
The explosive devices went off around 2 p.m. local time in a parking lot at the School of Hygiene, said Adelere Shinaba, police commissioner of Kano, Nigeria's second-largest city.
A suspect is in custody after being arrested on the scene, police said, and the suspect's car was discovered outside the school.
Police said they don't have a motive for the blast and are still investigating, but Boko Haram terrorists have targeted the northern Nigerian city in the past. The militant group says its aim is to impose a stricter enforcement of Sharia law across Nigeria, which is split between a majority Muslim north and a mostly Christian south.
Police swept the area around the school Monday with detection devices to make sure there were no additional bombs.
Eyewitnesses reported heavy military and police presence around the school.
CNN's Susanna Capelouto wrote and reported from Atlanta, and journalist Aminu Abubakar reported from Nigeria.