TRIPOLI, Libya (AP) — Gunmen ambushed a Libyan bank van and made away with over $50 million on a highway east of Tripoli, officials said Tuesday. The brazen heist underscores the weakness of the central government in the North African country, where authorities are struggling to control unruly militias.

A security official told The Associated Press that the Central Bank van had no guards accompanying it when was ambushed near the city of Sirte late Monday. The official news agency LANA, quoting a bank official who was with the van, said that a single carload of guards was escorting the money on its way from Sirte's airport to the local bank branch, but they were unable to resist the 10 attackers.

The money was a mix of foreign currency and Libyan dinars. LANA said that $40 million was in dinars and at least $12 million in foreign currency without specifying which. The official said the foreign currency consisted of $10 million in U.S. dollars and between 2 and 5 million euros ($2.7 to $7 million).

The two accounts could not immediately be reconciled. The official spoke on condition of anonymity because he was not authorized to speak to media.

LANA quoted Col. Khaled al-Akari, a security official in Sirte, as saying troops had closed the entries and exits of the city to try to apprehend the thieves. Sirte was a main support base for longtime dictator Moammar Gadhafi, and he made his final stand there before he was captured and killed in October 2011.

Libya lacks a centralized police force and a strong national army, so the government has to rely on militias who were part of the war against Gadhafi. But they often have conflicting political loyalties.

Assassinations and revenge killings are commonplace, fueled by longstanding grudges dating back to Gadhafi's rule, regional and tribal conflicts, and tensions between hard-line Islamists and other groups.

Much of the violence has centered on Benghazi, a city in the east that was the birthplace of the rebellion.

On Tuesday in Benghazi, gunmen opened fire on a protest sit-in made up of men belonging to the tribe of a controversial Gadhafi official who joined the rebels before being assassinated, killing two and wounding three, security officials said.

The motive of the attack was not clear. The protesters were demanding to know the results of the investigation into the 2011 killing of Abdel-Fatah Younis, who was Gadhafi's interior minister before defecting to the rebel side to help command the uprising.

Younis is considered by some to be a hero of the war against Gadhafi but some ex-rebels are hostile toward anyone who had ties to the regime, no matter what they did during the 2011 war.

Those officials also spoke anonymously as they were not authorized to talk to media.

Also in Benghazi, the head of a private bank kidnapped 45 days previously was found dead on the side of the road on the city's edge, senior security official Col. Abdullah al-Zaidi said. The banker had multiple bullet wounds in his head, chest and belly. His family said the kidnappers had asked for nearly $8 million as ransom.

Meanwhile, the deputy head of a security agency was shot dead outside a hospital in the eastern city by unknown gunmen, al-Zaidi said.