At least 15 Yemeni troops were killed and more than a dozen injured when suspected al-Qaeda militants attacked a heavily guarded government military base in southern Yemen Friday, Oct 19, security officials said, according to CNN.

The attack started when militants drove a vehicle loaded with explosives into the base in Abyan province, three local security officials said. The vehicle detonated near a crowd of troops.

A gun battle then ensued between militants and troops, culminating in the deaths of all nine militant attackers, security officials said.

The death toll for government forces climbed from initial reports of 12 to 15 after three soldiers died from their injuries. Officials warned the number could still rise further.

The violence comes a day after eight suspected al Qaeda fighters were killed in Abyan province by a U.S. drone strike, according to senior Yemeni security officials. Among those killed was Nader al-Shadadi, a senior leader within Al Qaeda in the Arabian Pensinsula, which has been blamed for numerous attacks in Yemen.