A lone attacker opened fire on the United States embassy outside Beirut on Wednesday, reportedly prompting a thirty-minute shootout with diplomatic security and Lebanese troops that only ended after the assailant was shot and captured, the military and embassy officials said.

Allegedly acting alone, the attacker first approached the diplomatic building in the northern suburb of Aukar sometime Wednesday morning. The responding forces shot him in both the leg and stomach before detaining him.

US officials revealed that one embassy security guard was hospitalized due to injuries sustained during the attack, but his condition was not elaborated on out of respect for his privacy.

While no motive has been confirmed, Lebanese media have said that the attacker wore a black vest painted with the letters “I” and “S” written in Arabic, indicating possible Islamic State affiliation.

A Syrian national, according to the Lebanese military, judicial, and security authorities, who spoke on the condition of anonymity due to the ongoing nature of the investigation, revealed that the gunman is a resident of the border town of Majdal Anjar.

Lebanese troops have since been deployed to both Majdal Anjar and the area surrounding the embassy. Despite raiding the suspect’s home and detaining some of his relatives, they found no further evidence of terrorist cell involvement.