A Yemeni guard opened fire Saturday at the employees of an international oil company in Yemen, killing an Indian national and seriously wounding an American, two Britons, a Tunisian and a Yemeni man, security and local officials said.

The incident took place at the Occidental Petroleum Corp. in the Shabwa province in the south of the country, some 300 miles south of the capital, San'a.

Shabwa province governor, Ali al-Maqqdishi, identified the guard as Jamel Mohammed el-Raaie, and said he was mentally disturbed.

A Yemeni security official, speaking on condition of anonymity because he was not allowed to give statements to media, said the wounded were transferred to a hospital in the Yemeni capital, San'a, for treatment.

The names of the victims were not known. The U.S. embassy in San'a could not be reached for comment. No further details were immediately available.

Occidental Petroleum Corp. is a California-based international company with oil and gas operations in three core areas — the United States, Latin America and the Middle East, including Yemen.