On Thursday, March 25th, there were more than 100 arrests of people that were suspected of having links with Al-Qaeda. These people were supposedly plotting attacks on security and oil installations in the Saudi kingdom. Out of these people that were arrested, there were 11 Saudis and one Yemeni. Many suspects were arrested in the southern province of Jazan, which is near the border with Yemen.
In October, there were two al-Qaeda fighters that tried to enter Saudi Arabia, dressed as women. This is when the network was first suspected of illegal and suspicious activity.
During this massive arrest, there were many cameras, weapons, documents and computers that were taken out of the possession of the men. These people were granted access and entry into the country because they had told officials that tey were looking for work or going to visit holy sites in Medina and Mecca.
At the moment, the investigaters do not know which oil installations were being targeted, and whether they were foreign or Saudi owned. The investigators were able to see that these men were going to perform suicide attacks, by the use of explosive belts.

http://english.aljazeera.net/news/middleeast/2010/03/2010324131416372358.html