Both incidents occurred in Park Forest, and police in that suburb have been called.
One student was accosted but the other was able to run away, according to a community alert posted on the Park Forest Chicago Heights School District 163 website, sd163.com.
"We are strongly advising that no student walk alone and that no student take short cuts and walk in areas where there is no traffic. Students should be alert and not respond to anyone they do not know for any reason," the school said in its online post.
