Al-Qaeda-linked suspects on Wednesday shot dead three air force colonels from the strategic Al-Anad air base in the southern province of Lahij, a military official told AFP.
"Gunmen shot dead three pilots with the rank of colonel north of Huta (the provincial capital) as they were heading towards Al-Anad air base," said the official, adding that the killers were "suspected of belonging to Al-Qaeda."
Officials said last year that Al-Anad air base was being used by US soldiers to train local forces in combating terrorism.
Al-Qaeda network was driven out of most of its strongholds across Yemen's south in an army offensive backed by US drone strikes last year.
At the peak of the offensive in May and June 2012, Al-Qaeda in the Arabian Peninsula -- classified by Washington as the global network's deadliest branch -- published a list of names of Yemeni pilots based at Al-Anad which it vowed to target for conducting air strikes against extremists' hideouts.
In October 2012, the Yemeni army foiled a car bomb attack on Al-Anad targeting American soldiers there, military officials said.