An Iowa principal who was critically injured in a school shooting put himself in harm’s way to allow his pupils to escape after the teenage gunman opened fire, authorities have said.

Perry High School principal Dan Marburger and six others, including two staff members and four teenage pupils, were injured in the shooting on Thursday morning that left one 11-year-old dead.

The 17-year-old pupil who opened fire at the school cafeteria in the city of Perry also died of an apparent self-inflicted gunshot.

The US state’s department of public safety said Mr Marburger, who is being treated in a Des Moines hospital, “acted selflessly and placed himself in harm’s way in an apparent effort to protect his students”.

Details have also emerged about other victims. The pupils who was killed was identified by authorities as sixth grader Ahmir Jolliff, who was shot three times.

The mother of one teenager posted on Facebook that her son was helped to an ambulance after he was shot multiple times. Perry Superintendent Clark Wicks said several people helped others to safety.

Mr Wicks said: “This is an extremely painful and difficult time for our entire school community, and in our grief, we will take time to remember.”

Yellow crime tape still lined the campus Perry High School shares with the town’s middle school on Friday, and flowers and stuffed toys were left at mini memorials.

Mr Wicks said classes will not resume in the district before next Friday at the earliest.

The news that seven pupils and staff suffered “wounds or injuries of varying degree” during the shooting was two more than authorities had previously spoken of.

Iowa division of criminal investigation spokesman Mitch Mortvedt said the number increased after investigators later learned about two more wounded faculty members.

All seven are believed to have been either wounded or grazed by bullets, and suffered injuries ranging from significant to minor.

On Friday, Mr Marburger and two students remained in hospital.

In a Facebook post on Thursday night, the principal’s daughter said he was in “surgery all day, and is currently stable”.

Claire Marburger called her father a “gentle giant” and said it was not surprising that her father tried to protect his students.

“As I heard of a gunman, I instantly had a feeling my Dad would be a victim as he would put himself in harms way for the benefit of the kids and his staff,” his daughter wrote.

“That’s just Dad.”

Mr Mortvedt said Mr Marburger, who has been principal since 1995, did some “pretty significant things” to protect others during the shooting, but did not release details.

Mr Wicks, the superintendent, said Mr Marburger was a “hero” who intervened with Butler so students could escape. Wicks said other staff also acted heroically, including Middle School Assistant Principal Adam Jessen who “carried a wounded student into a safe area”.

One mother, Bobbi Bushbaum, posted on Facebook that her son Corey was shot multiple times, suffering a fractured femur and wrist.

Mr Bushbaum said Corey was able to stumble to a nearby field after being wounded, and when she arrived, he was being helped toward an ambulance.

In the post, Bushbaum said her son underwent one surgery, but still had bullets in his body and will not be able to walk for weeks.

Bushbaum expressed thanks to those who helped pull Corey to safety, saying: “I would like them to know my son wouldn’t be here without them.”

Authorities said the suspect, identified as Dylan Butler, had a pump-action shotgun and a small-calibre handgun.

Mr Mortvedt told The Associated Press that authorities also found a “pretty rudimentary” improvised explosive device in Butler’s belongings, and that experts advised “it was something that they needed to disarm”. It was rendered safe.

Federal and state investigators are interviewing Butler’s friends and analysing his social media profiles, including posts on TikTok and Reddit. However, authorities have provided no information about a possible motive.