OAKLAND, CA (CBS) -- At least seven people are dead and three others wounded after a shooting rampage at a Christian college in Oakland, California. Police have interviewed the suspect and say he's being cooperative. Investigators say the gunman came to campus looking to hurt people.

Gunshots could be heard outside a Christian college in Oakland, California. Police say the gunman stood up in a classroom at Oikos University Monday morning and started shooting.

One witness, Deborah Lee, says, "I heard gunshot sounds like heard boom, boom, boom then right after that I heard one woman scream."

Dechen Wangzom was finishing a test when she heard gunshots. He says, "It's unforgettable."

She quickly locked the door to her classroom so the gunman couldn't get in. Wangzom says, "If I didn't lock the door I think I would be dead today."

Police rushed to the scene and surrounded the campus. Officers worked to rescue people trapped inside and pulled victims out on chairs and stretchers.

Crime lab investigators and a K-9 unit are still here at the college. They worked overnight collecting evidence.

Oakland Police Chief Howard Jordan says the suspect, 43-year-old One Goh, was expelled and came back to campus with a grudge against an administrator. Police chief Howard Jordan says, "He came here specifically to find people who were causing him problems, he did not find who he was looking for and went on a shooting."

This is the deadliest school shooting in five years. Oakland mayor Jean Quan says, "No American mayor wants to have this situation it seems over the last decade, we've gotten used to seeing senseless mass killings like this and we'll have to question the availability of guns."

Oikos caters to the area's Korean community. The mayor says its members are in pain and will gather for a memorial tonight to honor the victims.

The gunman drove to a shopping center shortly after the shooting and turned himself in.