SPARKS, Nev. – Two Sparks High School students were “messing with” an e-cigarette and caused an “explosion” in a school gym full of kids.

Washoe County School District police say an electronic cigarette is to blame for a small explosion and the incident caused the school to go into “Code Yellow.”

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According to Principal Kevin Carroll, a teacher saw a “fire spark” in the gym filled with 150 students. An evacuation was ordered and those students, along with others from neighboring classrooms, fled to the football field.

“I think you have to plan for the worst,” Carroll tells the Reno Gazette-Journal.

“I just hope it isn’t anything malicious,” he says. “It was put out pretty quickly.”

Some Sparks High School students say they heard an announcement of a bomb threat through the school’s intercom just before police responded to the call of the fire.

“A few minutes later, we went out and we evacuated to the football field,” says Juan Medina, an 18-year-old student.

“It was loud,” freshman Rodrigo Reynoso tells the Sparks Tribune. “I heard it, looked around and a teacher was getting us out. The fire went out real quick.”

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According to the paper, the e-cigarette malfunctioned “due to a non-standard power source that was attached to it.”

Despite causing a major disturbance, school district spokeswoman Victoria Campbell claims there was little harm done.

“Officers determined that there was no intent by the two students to cause the explosion,” Campbell tells the Gazette-Journal.

“They were messing with the e-cigarette,” she says, adding that no charges will be filed.

Many parents are upset because there was confusion about what was going on and there was a delay in receiving notification.

“After all that happened, they just told us right now,” Rosio Talavera said after the school lockdown was lifted. “I mean, why didn’t they tell us sooner as it was happening? Why wait until now?”

The school district was the site of a shooting two years ago.

“I was coming down to the school to drop off some lunch money for my daughter and she texted me that they were in Code Yellow,” Mireyna Pena tells the Tribune.

“My daughter was close at Sparks Middle School during the shooting. She was walking to school. It’s scary. I still want to get her. I want to know my kids are safe with me.”