PODGORICA, Montenegro (AP) -- The U.S. Embassy in the capital of Montenegro is warning Americans of "an active security situation" at the site.
Local media say that an unknown assailant hurled a hand grenade toward the embassy at around midnight local time and then killed himself with another explosive device. There was no official confirmation of the reports.
The area around the embassy has been sealed off by police.
The embassy is advising U.S. citizens to avoid the area, monitor local media for updates and avoid large gatherings.
Montenegro borders the Adriatic Sea in southeastern Europe and its capital is Podgorica. It joined NATO last year.