County fire inspector Steve Zermeno said the water bottles believed to have caused the sickness came from the school's vending machines. It was not immediately clear what the bottles contained, but it appeared to be a "bleach- like substance," he said.
Six of those who reported feeling sick were taken to a hospital for evaluation, Zermeno said.
The FBI dispatched its own hazardous materials team to the school, according to Laura Eimiller, spokeswoman for the bureau's Los Angeles field office.
The public relations director for The Pepsi Bottling Group said "there is absolutely no evidence that today's incident was caused by anything in our manufacturing process."
"We have examined and tested numerous bottles that were produced at the same time as those in this case and have found them to be free of any problems whatsoever," Jeff Dahncke said.
"The only products in question have been those that were previously opened and we are working closely with local authorities to determine exactly what happened. We are also running our own independent tests and we have no reason to believe this is anything but an isolated incident."
Twelve students were taken to four hospitals with complaints of headaches, nausea and dizziness, ABC7 reported. A doctor from Henry Mayo Newhall Memorial Hospital told ABC7 that all four students treated there were released after evaluation.
"Some may have been sick or ... junior high school kids may exaggerate a little bit," principal Pete Fries told ABC7.
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