(Reuters) - At least 18 people were wounded in two car bomb explosions that targeted a military unit in Libya’s eastern coastal city of Derna, sending plumes of black smoke into the sky, a medical source and residents told Reuters early on Sunday.

Residents said the car bombs targeted a military unit called Bulahati belonging to the eastern forces of the Libyan National Army (LNA) in the city center.

“We heard the first explosion, but we thought it was fireworks, then we heard the second,” one resident told Reuters by telephone.

“We found people around the Bulahati military unit and there was huge black smoke in the sky,” another added. “We then discovered it was car bombs.”

Derna, once a jihadist bastion, is about 292 km (182 miles) distant from Libya’s second city, Benghazi, and was declared to be under the complete control of Khalifa Haftar’s LNA in June 2018.

After the ouster of longtime ruler Muammar Gaddafi in a NATO-backed uprising in 2011, militant groups Al Qaeda and Islamic State have used the oil-rich country as a base for attacks, exploiting its chaos and lack of security.