A gunman, allegedly identified as Chris Harper-Mercer by multiple law enforcement sources though his name has not yet been officially released, stalked onto an Oregon college campus on Thursday and opened fire, killing nine people and wounding seven before police shot him to death, authorities said.

The suspect, who witnesses say fired dozens of shots in a classroom full of screaming students, was slain in an exchange of gunfire with two police officers in at Umpqua Community College in Roseburg, ending the rampage.

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Stacy Boylan, the father of an 18-year-old student who was wounded but survived by playing dead, told CNN his daughter recounted her professor being shot point blank as the assailant stormed into the classroom.

"He was able to stand there and start asking people one by one what their religion was," Boylan said, relating the ordeal as described by his daughter. "'Are you a Christian?' he would ask them. ... 'If you're a Christian, stand up. Because you're a Christian, you're going to see God in just about one second,' and he shot and killed them. And he kept going down the line, doing this to people."

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Authorities offered no explanation for the gunman's actions.

"The law enforcement investigation into the shooter and into his motivations is ongoing," Douglas County Sheriff John Hanlin said at an afternoon news conference. He also said three of the wounded victims were hospitalized in critical condition.

President Barack Obama, speaking just hours after the rampage, said the mass killings should move Americans to demand greater gun controls from elected officials.

"Somehow this has become routine," a visibly angry Obama said. "The reporting is routine. My response here, at this podium, ends up being routine. ... We’ve become numb to this."