Montenegro’s government said Thursday that an attacker threw a hand grenade at the U.S. Embassy in the capital of the Balkan state and then killed himself with another explosive device, Politico writes.

The area was sealed off by police, and the embassy warned Americans to avoid the area because of “an active security situation.”
Montenegro’s government said the unknown assailant hurled the grenade into the embassy compound around midnight and then killed himself with another explosive device. No one else was apparently hurt and there was no major damage.

“The Embassy is currently conducting an internal review to confirm the safety of all staff,” the State Department in Washington said.

Montenegro borders the Adriatic Sea in southeastern Europe and its capital is Podgorica. It joined NATO last year despite strong opposition from its traditional Slavic ally Russia.