The Massachusetts Institute of Technology (MIT) said Saturday its campus was on lockdown after reports that a man carrying a rifle was spotted in a campus building. The MIT, a famous private research university located in Cambridge of the U.S. state of Massachusetts, said in a statement that several law enforcement agencies had responded. It advised students and workers to stay indoors and report suspicious activity to campus police. No further details were immediately available. US schools have been plagued by a rise of violence involving guns, which has led President Barack Obama to launch a new offensive for tightening gun control. On December 14 last year, 26 people including 20 schoolchildren at the Sandy Hook Elementary School in the U.S. state of Connecticut were killed by a single gunman in one of the worst school shootings in the country's history.