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 devicerocked 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.