The Douglas County Sheriff's Office says it likely knows the identity of the man who walked into a morning writing class a Umpqua Community College Thursday, opening fire and killing sevreal people.

But Sheriff John Hanlin won't say the name of the shooter, also killed in an exchange of gunfire with police. Not now, he said. Not ever.

"Let me be very clear: I will not name the shooter," Hanlin said in a message released late Thursday. "I will not give him credit for this horrific act of cowardice. Media will get the name confirmed in time ... but you will never hear us use it. "

By then, the name had indeed been widely reported: The killer was identified as Chris Harper Mercer, according to a government official who was not authorized to speak publicly and provided the name on condition of anonymity. The gunman died following a shootout with police.

"We would encourage media and the community to avoid using it, repeating it, or engaging in any glorification and sensationalization of him," Hanlin said. "He in no way deserves it. Focus your attention on the victims and their families and helping them to recover."

The sheriff said he didn't expect to release the names of any victims until at least Fridays, as his office continued following its protocols for a mass casuality incident. Notifications to families would be a the priority, he said.

"We do know that we have at least two heroic officers who responded into the building within minutes and exchanged gunfire with shooter," he said. "(Oregon State Police are) handling that aspect of the investigation and will release any information about that officer-involved shooting at some point in the future."

Deputies and victim specialists were working with families Thursday as the victims were identified. Hanlin encouraged any with questions or tips to call 1-800-CALL-FBI and hit option 7.

Tactical teams and bomb technicians had cleared all buildings on campus, he said, and officers were working to clear hundreds of vehicles still on campus. Evidence teams from FBI the FBI and state police were working to process the crime scene.

At least nine people were killed by the gunman and seven others were wounded, according to the most recent reports — figures reported by authorities range from seven to 13 dead in the hectic hours after the shooting.

One witness said the attacker demanded to know students' religion before shooting them on Thursday, the fourth day of class at Umpqua Community College, according to a report by the Associated Press.

Another witness reportedly said a teacher was struck in the head.

Police have not yet whether they know of any motive.

Mercer lived in a nearby apartment complex, the AP reports.

Before the shooting, a posting on the message-board site 4chan included a photo of a crudely drawn frog used regularly in Internet memes with a gun and warned other users not to go to school Thursday in the Northwest, according to the AP. The messages that followed spoke of mass shootings, with some egging on and even offering tips to the original poster. It was unclear if the messages were tied to the shooting because of the largely anonymous nature of the site.

The Associated Press contributed to this story