Five schools in the Adams 12 Five Star School District were placed on lockout Thursday morning due to police activity in the area.

Thornton Police tweeted that officers are investigating a robbery in the area of Colorado Boulevard and East 136th Avenue. No additional information about the robbery or potential suspects was released.

Mark Poshak, a spokesperson for Adams 12 Five Star Schools, said the following facilities are on lockout:

-Horizon High School
-Rocky Top Middle School
-Prairie Hills Elementary School
-Tarver Elementary School
-Eagleview Elementary School

A lockout means that nobody is allowed in or out of a building, though it’s business as usual inside, Poshak said.

The lockout began at around 8:25 a.m.