An unknown assailant threw an explosive device into the U.S. Embassy in Ukraine capital Kiev early on 8 June's morning.
There are no immediate report of damage within the embassy premises and no report of casualties.
Police said they are treating the incident as a suspected terrorist attack, Russian Today reports.
The explosion took place at 12. 05 a.m. local time, according to a statement issued by the Kiev Police.
The police immediately dispatched a rapid response unit to the embassy premises.
An investigation has been launched into a suspected terrorist attack.