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A sign at the edge of campus welcomed students and staff back to Umpqua Community College Sunday in Roseburg, Oregon. Getty Images

The use of deadly force by two detectives against a gunman in Oregon last week was justified, state police said Wednesday while announcing the conclusion of the investigation into how officers handled Thursday's mass shooting at Umpqua Community College. Det. Sgt. Joe Kaney and Det. Todd Spingath, both of the Roseburg Police Department, wounded the suspect before he killed himself, Douglas County District Attorney Rick Wesenberg said at a news conference.

"These men saved lives this day," Wesenberg said. But Roseburg Police Chief Jim Burge added, "They do not want to be heralded as heroes. They feel they are only first responders who got there first and did a job they were trained and entrusted to do."

The police's update Wednesday gave details about the timeline of events last week when Chris Harper-Mercer, 26, opened fire in a classroom at Umpqua and fatally shot nine people. Douglas County received its first 911 call about the active shooter at 10:38 a.m. PDT, and Kaney and Spingath responded because they were only five miles away. They met two other troopers on campus by 10:44 a.m., at which point they saw the shooter and "ran towards [sic] the sound of gunfire," according to a news release posted on FlashAlert. The detectives were in plain clothes without bulletproof vests on.

Kaney and Spingath hesitated before firing to avoid hitting any students, then moved to have a better vantage point. Harper-Mercer shot multiple rounds at the detectives, who fired three rounds back at him. One hit the shooter on the right side. "Once the shooter was wounded, he entered the classroom again, went to the front of the classroom and shot and killed himself," the release read.

The detectives weren't the only people to reportedly challenge Harper-Mercer. Veteran Chris Mintz, a student at Umpqua, was shot seven times while attempting to block the suspect from hitting more victims, according to U.S. News and World Report. He was expected to survive.