SAN’A, Yemen (AP) – A Yemeni guard opened fire Saturday on a group of foreign oil workers shortly after they landed at a company airstrip, killing one and wounding five – including an American, officials said.

The shooting took place at the Occidental Petroleum Corp. in the southern Shabwa province, some 300 miles south of the capital, San’a. The provincial governor, Ali al-Maqqdishi, said the guard was mentally ill.

The American Embassy in San’a confirmed the attack in a message posted on its Web site and said the American was “critically injured.” The embassy canceled travel to the bordering Shabwa and Mariba regions “for the near future” and recommended that Americans avoid the area.

A Yemeni security official, speaking on condition of anonymity because he was not allowed to give statements to media, said the victims were all coming off a plane that was landing at the oil company’s airstrip in Shabwa when the guard randomly opened fire at them.

The American statement did not mention the other casualties, but Yemeni officials said the worker killed in the attack was an Indian national; the others who were wounded included two Britons, a Tunisian and a Yemeni man.

Occidental Petroleum Corp. is a Los Angeles-based company with oil and gas operations in three core areas – America, Latin America and the Middle East, including Yemen.

Also Saturday, Yemeni security officials said they arrested two men suspected of al-Qaida links who confessed to an attack on an oil pipeline Tuesday near the port city of Aden. The men tried unsuccessfully to blow up the pipeline with TNT, the officials reported, speaking on condition of anonymity according to government policy.