(CNN) -- The Libyan government on Sunday declared a three-day national mourning period after the country's first suicide bombing since the fall of the Gadhafi regime more than two years ago.
At least 13 people were killed in the attack on a checkpoint leading to the eastern gates of Libya's second city, Benghazi, early Sunday, the government said.
Most of those killed were soldiers and members of the security forces, the government said. At least two others were still missing in the aftermath of what has been described as a powerful blast.
A security official told the state news agency LANA that a suicide bomber rammed his vehicle into the Barsis checkpoint -- about 50 kilometers (30 miles) east of Benghazi -- killing and wounding security forces and civilians who were in the area.
The security situation in Benghazi has been worsening over recent months with a noticeable uptick in bombings and assassinations that have mostly targeted members of the security forces.
While no one has claimed responsibility for these attacks, many residents blame the violence on Islamist militants in the eastern region, and some of these groups have ties to al Qaeda.
People in Benghazi and the eastern city of Derna, angered by the increasing bloodshed, have recently taken to the streets protesting against extremist groups.
One group many have accused of being responsible for attacks on the security forces is Ansar al-Sharia, the same group the United States believes attacked its consulate in Benghazi last year, killing U.S. Ambassador Christopher Stevens and three other Americans.
Ansar al-Sharia has denied involvement in the attack on the consulate and other acts of violence targeting security forces.
Last month fierce fighting erupted in Benghazi between soldiers from the army's special forces, who have been trying to secure the city, and members of Ansar al-Sharia. At least nine people were killed in the rare confrontation between security forces and militants.
The weak central government has been struggling to secure the country, especially the city of Benghazi where militants have attacked diplomatic missions forcing western countries to shut down their consulates.
The United States, the United Kingdom and other countries advise their nationals against traveling to Benghazi.
Earlier this month, an American teacher in the city was shot dead while jogging. No one has claimed responsibility for his killing.
As locals and security forces began confronting militants, analysts monitoring the violence trends in Benghazi have been concerned about an escalation in violence and shift in tactics used by these groups.
"This cowardly act is an attempt to obstruct the strenuous efforts made by members of the national army, with the Thunderbolt (special) forces at the forefront, to establish security and preserve the life of citizens in Benghazi," the government said in its statement.