Officials are urging parents in the Governor Mifflin School District to speak with their children immediately.
Police say synthetic marijuana was being sold about a 1,000 feet away from the high school.
"Synthetic marijuana is very dangerous, and we want to make sure that it is unavailable to our youth," said John Adams, Berks County district attorney.
Thursday afternoon police arrested Alpeshkumar Patel, as well as Nileshkumar Patel.
Both men are citizens of India, officials said.
But police say Nileshkumar Patel was in the country illegally, and had a federal warrant for deportation.
"What is very concerning about this specific situation," said Adams, "is the fact that these two individuals, who are not citizens of our country, were selling drugs within close proximity to the Governor Mifflin School District."
During an investigation, detectives say they were able to purchase $84 of the illegal substance.
"When detectives went into the E-Z Shoppe they confiscated approximately 10 grams of synthetic marijuana, $7,000 in cash and other related drug paraphernalia," said Adams.
Parents in the area said they were upset by the news.
"I find that incredibly upsetting to find out, that close to our school, where our kids are hanging out all the time, would be doing something like that," said Kiertsen Yocum.
"It is just absolutely sickening. It's terrible. My child walks to school every day, and that's going on a few feet away? It's terrible," said Mary Pahl.
The store owner declined to comment.
Both of the suspects, if convicted, face two years in jail and deportation to India.