Thirteen people were dead and more than about 20 others were injured after a gunman opened fire Thursday morning on the campus of Umpqua Community College in southwest Oregon, authorities told NBC News.

It wasn't immediately known whether the gunman was among the dead after the shooting near Roseburg, which was called in at 10:38 a.m. (1:38 p.m. ET), officials said. State Attorney General Ellen Rosenblum told NBC News simply that he had been "neutralized."

Mercy Medical Center in Roseburg said it was treating nine patients, with three more expected. Sacred Heart General Hospital in Eugene, a major trauma center, told NBC News it was expecting three patients by helicopter.