RIYADH (Reuters) – Saudi security forces surrounded a building in Jeddah on Monday after coming under fire when they tried to arrest four suspected militants holed up inside, an interior ministry spokesman said.

“Security forces have been besieging a building in Jeddah for nearly six hours. Inhabitants of the building were evacuated as the operation is still under way,” the spokesman said.

The four suspects started firing at security forces when they tried to enter the building in the Red Sea city and arrest the men, he said, adding that it was too early to say whether they were on a list of wanted militants.

Saudi Arabia has been battling a campaign of violence by militants linked to al Qaeda who want to topple the pro-U.S. monarchy and expel foreigners from the birthplace of Islam.

He said security forces had arrested seven suspects in Jeddah on Sunday, but so far there was no link between the arrests and Monday’s siege.

“The seven that we arrested on Sunday are not on the wanted list but are being interrogated,” he said.

In June, authorities said the security forces had arrested 42 suspected Islamist militants in raids over the previous few months throughout the kingdom, the world’s biggest oil exporter.