CHICAGO (CBS) — Police say 18 students were taken to hospitals Thursday after they took an undetermined prescription medication at school.

Four students have been arrested.

Police say the four boys who were arrested and charged with possession were also treated for taking the prescription pills.

The fire department says it took 12 students to hospitals.

All of the children were listed in stable condition, WBBM Newsradio’s Steve Miller reports.

Others went to the hospital on their own.

Police say a total of 15 from the Air Force Academy High School, 3630 S. Wells St., went to hospitals, and three from McClellan Elementary, 3527 S. Wallace St, went to hospitals.

Those two schools are just blocks apart, near U.S. Cellular Field.

Chicago police say the Illinois Crime Lab is trying to determine the type of medication.

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