A Southern California mosque was vandalized early Thursday with a spray-painted threat and other graffiti that was noticed by authorities even before the paint was dry.

An officer spotted the slurs and expletives painted on the Islamic Center of Cypress before dawn, Police Sgt. Tom Bruce said.

The painted lettering was about 4 or 5 feet tall and read, in part: "We will kill you all," Orange County Human Relations Commission said.

Police said there were no witnesses and the incident was not caught on surveillance video. The paint was still wet to the touch, Bruce said, and a crew was called in to clean it off.

Human relations commission director Rusty Kennedy said it was likely the act was prompted by President Barack Obama's trip to the Middle East. The graffiti was done about an hour after Obama's much-anticipated speech at Cairo University in Egypt, which was aired live.

But Ahmed Mehtar, the mosque's imam, said he wasn't sure of the link.

"We don't know the reason behind what was done," he said in a brief phone interview with The Associated Press. "It is upsetting but since we don't know why it happened, it's hard to say."

Shakeel Syed, executive director of the Islamic Shura Council of Southern California, said there is a small Muslim community in Cypress. The mosque is one of the smaller ones in Orange County, with anywhere from 50 to several hundred attendees depending on the day and service, Syed said.

Kennedy said there were 79 hate crimes in Orange County in 2008, down slightly from 82 the previous year.