The photo of the suspect of a shooting rampage at a northern California college has been released. Police are searching a nearby waterway for the weapon used by the gunman.

Police investigators work at Oikos University, the site of shooting accident in Oakland, a city in the state of California, the United States, on April 3, 2012. [Xinhua]

The suspect, One L. Goh, is a 43-year-old South Korea native. He appears to have spent several weeks planning the attack. Goh is refusing to say where the semi-automatic handgun was left after Monday's attack at Oikos University.

Police investigators work at Oikos University, the site of shooting accident in Oakland, a city in the state of California, the United States, on April 3, 2012. [Xinhua]

Investigators are using a sonar robot and other equipment to search a shoreline located near the school. Authorities say it's important for local safety to find the weapon. The attack left six students and a secretary dead.