Threat of violence at Burlington City High School, heavy police presence on campus

School officials at Burlington City High School say there was a heavy police presence at the school due to a threat that was made on Wednesday. 

Authorities say there was a threat of an act of violence from inside the school prior to dismissal. 

Students were briefly held at the school to give police time to secure the surrounding area, officials say. 

School was dismissed a short time after and officials say all students were released safely. 

The Criminal Investigation Division and school officials are actively investigating this situation.