Bulletproof shelters have been installed in an American primary school to protect children from violent intruders.

The units, which double as storm shelters, can hold up to 35 students and two teachers.

The school, in Healdton, Oklahoma, was one of a number of schools to be subject to a copy-cat threat in the wake of the recent mass shooting at a Florida high school where 17 people died.

"When tornadoes strike, and Lord help us, when you have an intruder on campus, to know that you have somewhere to go quickly for the safety of your students, it's very relaxing," Superintendent Terry Shaw told Koco 5 News, a local news outlet.

Seven armoured lockable units, which double as storm shelters, have been installed inside Healdton Elementary School and two larger ones built in the middle school.


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Plans are in place for shelters to be erected at the local high school.

Mr Shaw tested the shelters by locking himself inside one of the rooms before it was was shot at using automatic weapons.

Video footage of the test shows it being marked by bullets on the outside as the superintendent stands inside.

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"I volunteered. I did not feel comfortable putting these in my buildings if I wasn't willing to do it myself. So I offered to go inside," Mr Shaw told Koco 5 News.

"It was very surreal, but I felt very comfortable. Very safe."

The shelters are the first to be installed in America. Shelter-In-Place, the maker of the units, have since installed them in other districts.

'I want to feel safe in my school'

The firm's website advertises the shelters as being capable of sustaining an EF5 tornado, which would see winds exceeding 200mph, as well as earthquakes and hurricanes.

The shelters are also described as being resistant to man-made dangers such as gunfire and explosives.

Shelter-In-Place suggest the rooms can be used as a quiet reading area at other times. They have their own lighting, padded benches, a "plush carpet" and internal and external cameras.

School children have carried out drills to test how they would react during a storm or an attack by a gunman on the school grounds.

One local mother said she regretted that such an apparatus was needed.

"You think those things are never, ever gonna happen in your school, but, unfortunately, they do," Ms Hudson told Koco 5 News.