Police in the Ukrainian capital Kiev said on Thursday someone hurled an explosive device onto the grounds of the U.S. embassy.

Police said in a statement no one was injured when the device detonated on the embassy’s lawn in the late hours on Wednesday. The U.S. embassy’s compound on the western outskirts of Kiev is surrounded by a high fence, making it difficult for a passer-by to hurl something there.

Police did not identify the explosive device but said they were treating the incident as an act of terrorism.

In a subsequent statement, the embassy confirmed the incident involved a “small incendiary device,” and added that it does not consider it a terrorist act.

(AP)