Gunmen raided two banks in the port town of al-Shahr in Yemen's eastern Hadramout province and stole about 52 million riyals ($240,000) on Tuesday, the defense ministry's news website said.
Security is poor in Hadramout, a province awash with arms where tribal structures prevail. Its inaccessible terrain of arid valleys and desert have long attracted al-Qaida militants and criminals alike.
The 26sep.net website quoted an unnamed local source as saying that three cars with 25 gunmen raided the two banks in al-Shahr city simultaneously. One guard was killed and another was wounded.
The source said the group took nearly 32 million riyals from one bank and nearly 20 million riyals from the second bank. There was no immediate information on the identity of Tuesday's attackers.
A day earlier an army general escaped an ambush after suspected al-Qaida militants planted bombs on a road on which the general's convoy was traveling near al-Qatan in Hadramout.
In May, militants attacked the Hadramout city of Seyoun, targeting seven locations, including the main military posts, the police headquarters, bank branches and the airport.
Local officials suspected the attackers were al-Qaida militants retaliating for a government offensive against them. At least 27 people, including 20 militants, died in the firefight.
Yemen has been in turmoil since 2011 pro-democracy protests forced long-ruling President Ali Abdullah Saleh to step down.