Police are still trying to determine exactly what kind of a chemical device was used and exactly who did it.
Police have been on campus all day at Lockport Township's central campus to do a thorough search. They have not found anymore devices.
The incident began about 7:40 a.m. Monday morning.
The school week had barely begun when police and the fire department were called to the freshman campus for what was first reported as an explosion in the second floor hallway.
"We didn't hear anything, we didn't smell anything, we didn't see anything. We didn't even know anything was going on until they literally had to tell us," said Kayla Tran, student.
It was a plastic bottle with some type of chemical inside.
"The initial reports were that a black smoke appeared and some fluid that they got on their skins," said Chief Bill Kendizora, Lockport Police Department.
Sixteen students and one teacher were treated and eventually released for their injuries.
The school was placed on lockdown for over two hours while investigators made sure everyone was safe.
"I knew if it was something serious like a gas leak or something we would have been out of the building so I wasn't really concerned," said Thomas Hatzopoulas, student.
While students remained calm inside, parents panicked outside, trying to get information and also trying through cell phones to speak with their kids.
"Did we hear from the school? No. Okay. We had to hear it from the media that our children were in danger and I'm sorry, I got a problem with that," said Kathleen Zidek, parent.
Around 11:30 a.m. on Monday morning, the lockdown ended and students were dismissed for the day.
Students believe another student set off the chemical device.
"Any time we have injuries to students and staff, I wouldn't consider that a prank at all. So we are doing everything we can to find out who is the perpetrator of this incident," said Kendizora.