JALALABAD, Afghanistan — Suicide bombers targeted an Education Department building in the eastern Afghan city of Jalalabad on Wednesday, striking the commercial hub for the second time in 24 hours and killing at least 12 people.

No group immediately claimed responsibility for the attack, the latest in a series of strikes on educational sites in the province. But suspicions quickly fell on the Islamic State, which has a foothold in the region and has announced its plans to attack schools in retaliation for airstrikes and other military operations that have killed its fighters.

Gen. Ghulam Sanayee Stanekzai, the police chief of Nangarhar Province, which includes Jalalabad, said that a single assailant had shot and killed guards at the precinct’s Education Department before detonating explosives hidden in a vest. But a spokesman for the governor later said there had been three assailants.

“In addition to the three attackers, 12 people were killed, including two security members of the Afghan security forces,” said the spokesman, Attaullah Khogyani. Nine others were wounded.