The governor of Minnesota denounced an attack on a mosque the previous day as a “terrible, dastardly, cowardly” act of terrorism.

“It’s an act of terrorism, a criminal act of terrorism,” the governor, Mark Dayton, said on Sunday during a visit to the mosque, Dar Al Farooq, in Bloomington. “I hope and pray that the perpetrator will be caught and prosecuted to the full extent of the law.”

The explosion, which the F.B.I. said was caused by an improvised explosive device, rocked the mosque early Saturday morning just as congregants began to gather for prayers. No one was injured, but the building sustained minor damage close to the site of the explosion.

The mosque’s executive director, Mohamed Omar, said on Saturday that the explosion was set off “in the direction of the imam’s room.” He said that a member of the congregation had rushed outside after the device was thrown in and had seen a truck rushing away from the mosque’s parking lot.