One guard was killed and four others injured on Thursday when gunmen stormed the National Bank's branch in Yemen's southern port city of Aden, according to sources.
Eight masked militants attacked the bank, with the first four breaking into the building and the other four shooting randomly, witnesses said.
"All eight attackers escaped. One of the bank's security guards was dead" they added.
The manager of the government-owned National Bank refused to open the safe and was critically injured in the armed robbery attack, one of the bank workers said.
No group immediately claimed responsibility for the armed robbery attack.