The US Embassy in Montenegro was reportedly rocked by blasts after a group of attackers hurled grenades in the area.
One of the attackers has been reported dead.
While it is not known if the attack is under way, a security alert has been issued and residents have been asked to avoid the area.
"The US Embassy in Podgorica advises US citizens there is an active security situation at the US Embassy in Podgorica. Avoid the Embassy until further notice," the alert said. The worried US citizens have also been asked to "avoid large gatherings" and "follow the instructions of local authorities."
The attack was confirmed to Express UK by an eyewitness who also said that a person had died outside. "Someone died outside the Embassy. Car fire or something. Someone was throwing grenades at the Embassy and one blew up and killed himself," the witness explained.
The embassy reportedly employes about 34 Americans and 134 locals.