The suspect died of an apparent self-inflicted gunshot wound, sources said.
PERRY, Iowa -- A student was killed and five people injured in a shooting Thursday morning at Perry High School in Iowa, officials said.
The suspected shooter -- a student at the high school -- is also dead of an apparent self-inflicted gunshot wound, according to Mitch Mortvedt, assistant director of the Iowa Department of Public Safety's Division of Criminal Investigation.
Five students were among the shooting victims, including a sixth grader who died, Mortvedt told reporters during a press briefing Thursday afternoon.
Perry High School Principal Dan Marburger was among those shot, the Perry Community School Board and the Easton Valley School District confirmed. The extent of his injuries is unclear.
Five patients were being treated at Iowa Methodist Medical Center, according to a hospital spokesperson. One victim was in critical condition, while the other four were stable, Mortvedt said.
An active shooting incident was reported at approximately 7:37 a.m. local time, police said.
"Police officers responded within minutes. They immediately made entry and witness students and faculty either sheltering in place or running from the school," Mortvedt said.
The suspected shooter -- identified as 17-year-old Dylan Butler -- was found dead with a pump-action shotgun and a small-caliber handgun, Mortvedt said.
The suspect "made a number of social media posts in and around the time of the shooting," Mortvedt said. "Law enforcement is working to secure those pieces of evidence."
The suspect is believed to have acted alone, he said.
A "rudimentary" explosive device was also located in the school and rendered safe, Mortvedt said.
"There is no further danger to the public. The community is safe," Dallas County Sheriff Adam Infante told reporters during an earlier press briefing.. "We're just now working backwards, trying to figure out everything that happened and make notifications."
Jody Kurth told reporters that her stepson was struck in the back and arm in the shooting, but is "doing really well."
She said her daughter texted her about the shooting.
"It was absolutely horrifying, that's one of the worst moments of my entire life," she said. "But the best phone call I got was saying that they were OK."
"I really never thought that Perry would have an issue like this," she added.
The shooting occurred before the school day had started, and there were very few students and faculty in the building, "which I think contributed to a good outcome in that sense," Infante said. Thursday was the first day of school back from the winter break.
The school district will be closed on Friday, school officials said.
The FBI's resident agent at its Des Moines office has responded to the scene to assist the Iowa Division of Criminal Investigation, the FBI said. The Bureau of Alcohol, Tobacco, Firearms and Explosives is also on scene.
The U.S. attorney general has been briefed on the incident, a Department of Justice spokesperson said.
Perry is located in the suburbs northwest of Des Moines.
Iowa Gov. Kim Reynolds said the "senseless tragedy has shaken our entire state to its core."
"Our hearts are heavy today and our prayers are with the Perry community," she said during Thursday afternoon's press briefing. "This strikes at the heart of everything we hold dear."
President Joe Biden is monitoring the shooting, the White House said Thursday.
"Our hearts break for the families of the victims in yet another act of senseless gun violence," White House press secretary Karine Jean-Pierre told reporters.
"It's only the fourth day in the year, in the new year, and we are already faced with yet another horrific school shooting. And the question that we ask, is when will enough be enough?" she said.
ABC News' Jack Date and Luke Barr contributed to this report.
This is a developing story. Please check back for updates.
The Associated Press contributed to this report.