Kabul, Afghanistan (CNN) -- At least 25 people were injured Sunday when a man on a motorbike hurled a grenade at a high school in northern Afghanistan, an official said.
The blast injured at least 17 students at the school -- three of them seriously -- said Ahmad Jawed Bedar, a spokesman for the governor of Faryab province.
Police arrested the suspect two hours after the attack, which occurred around noon Sunday, he said.
Later Sunday, an explosion in the Afghan capital of Kabul injured three police officers, a local police official said.
Hashmat Stanikzai, a spokesman for Kabul police, said a device exploded in Kabul's Dehmazan Square near a traffic police station around 12:30 p.m.
The officers were slightly injured, Stanikzai said.