The Roseville Community Schools district is on high alert after multiple shell casings were found at two schools on Tuesday and Wednesday.

In a statement, Deputy Superintendent Dave Rice says two casings were found Tuesday in the media center at Green Elementary School. Rice says the school contacted police, and students who were in the room were interviewed. 

Officials say later that day, shell casings were found on the bleachers at Roseville High School. Two more shell casings were found on Wednesday in a shop class at the school.

Rice says a shelter-in-place was issued at the high school as police interviewed students. Officials say a K-9 unit searched the schools did not uncover any other items.

"To this point, there has been nothing found as we continue to use an overabundance of caution for the safety of our students and staff. Parents at the two schools were notified of the situation via phone, text, and email and were informed students would not be released at this time," Rice said in the statement.

Roseville High School principal Jason Bettin says there were no threats reported toward students, staff or the school. Bettin urges parents to pay attention to their children's cellphones and social media usage and store all ammunition in their homes.

"It is unfortunate that this is our second day in a row dealing with this type of issue," Bettin said in a statement. "Recent headlines in the news from the metro area have shown we are not alone in dealing with this exact issue. It all appears to be connected to online activity encouraging students with access to bullets to "drop them in school" to prompt the exact type of response we had today."