(CNN) - The man who authorities believe opened fire at Oregon's Umpqua Community College on Thursday is dead, Douglas County Sheriff John Hanlin told reporters.
No police officers were injured, but preliminary information indicates 10 people were killed and more than 20 others injured in the shooting, according to Oregon State Police spokesman Bill Fugate.
The suspect was a 20-year-old man, according to Oregon Gov. Kate Brown.
Investigators are examining social media postings they believe were made by the suspect, according to a source with knowledge of the investigation.
The night before the attack, the alleged shooter appears to have had a conversation with others online about his intentions, the source said.
"We arrived to find multiple patients in multiple classrooms. Law enforcement was on scene and had the shooter neutralized," Douglas County Fire Marshal Ray Shoufler told CNN.
He said that two patients died while being transported to a hospital.
The shooting appears to have started in one building before the gunman moved to the school's science building, the source told CNN. Those killed and wounded were found in at least two classrooms.
Mercy Medical Center posted on Twitter that it had received nine patients, with three more on the way. The extent of their injuries was not known.
Three victims arrived at PeaceHealth Sacred Heart Medical Center at RiverBend in Springfield, about 70 miles north of the shooting scene. Two more are on their way, that hospital tweeted.
ATF agents were also on scene and canine teams are en route to search for explosives, fire arms casings and ammunition, a spokesman said. The FBI was en route.
It's not a traditional institution of higher learning, as the average age of its 13,600 students was 38 during the 2013-2014 school year. Only 740 of those were full time, 2,437 were part time and more than 10,000 fell under the umbrella of "community education."
It first began teaching classes out of rented facilities in 1961. Elton and Ruth Jackson donated 98.5 acres to house the campus in 1965.
President Barack Obama, expressing deep anger and impatience, on Thursday bemoaned yet another mass shooting that left a community "stunned with grief" and warned that America was becoming "numb" to such violence.
"Each time this happens, I am going to say we are going to have to do something about it -- and we are going to have to change our laws."