In a follow-up tweet, the department said, "two adult victims have been located and transported to area hospitals. It is believed the suspect is no longer on scene, and investigators are working to develop additional info." ATF Denver confirmed in a tweet that it was on scene. 

Denver Public Schools (DPS) tweeted that a lockdown was in place and all students were in their third period classrooms. In an update, a controlled release of students would begin once DPD allows. Parents will be able to pick up their children at 17th and Esplanade. 

"Students who drove will be escorted to their cars in the parking lot & can leave. Students who ride the bus will be held until their bus arrives," the tweet said. 

This is breaking story. Check back for updates.