The search wasn't the most successful ever, especially considering gunshots may or may not have been fired while the four U.S. military personnel were at a routine checkpoint. 

Here's what we know for sure: the Associated Press reports four U.S. Marines were detained Saturday by Libya's Interior Ministry. There was an "incident" at a checkpoint near Sabratha, about 40 miles from Tripoli, the capital, officials told NBC News, which led to the mix-up. The New York Times reports the four detained Marines were special forces assigned to diplomats in Tripoli researching potential escape routes for their protection detail. 

So, what happened at the checkpoint? No one really knows for sure. "Reports of gunfire could not be confirmed," the Guardian notes. "Circumstances under which the four were detained remains unclear and no one was reported injured in the incident," writes Al-Jazeera. Something happened, though, and it angered Libya enough to detain the Marines for about four hours. 

"After running into a problem at a checkpoint — many of which are run by local militias — they were detained and later moved to the Ministry of the Interior," officials told The New York Times. 

The Marines were under "Libyan government custody," according to State Department spokeswoman Jen Psaki, indicating they were never detained by security forces or the military. The State Department called the Libyan government to sort through the issues, and the Marines were eventually released to the Embassy's front door.