Two Americans, two Britons and an Australian were killed in an attack on an engineering firm in the Saudi Red Sea port of Yanbu on Saturday, security sources said.

According to the sources, all the five Western engineers worked for ABB Lummus, a subsidiary of Swiss-Swedish engineering and oil services giant ABB.

The Saudi Interior Ministry earlier said in a statement that four men entered the headquarters of a Saudi contractor in Yanbu Saturday morning and fired at random at Saudis and foreigners.

"There were a number of deaths and injuries among Saudis and foreigners," it added.

Saudi security forces chased the gunmen who took refuge in residential areas and hijacked some cars. Three of them were killed and a fourth was wounded, the statement said.

It was the first such attack on a Western oil facility in Saudi Arabia, the world's largest oil exporter.

Yanbu, about 250 km north of Jeddah, is home to much of the kingdom's oil refining and petrochemicals industries together with nearby Jubail.