BOSTON -- Students at Norwood High School were dismissed early on Monday after a threatening note was found in the school.

The note was found at about 10 a.m., Norwood police said. The details of the threat were not immediately known.

This is the third time in as many weeks that there has been a threat against the school. Police said the first two threats were hoaxes, and they do not believe Monday's is legitimate, either.

Police and school officials are investigating the threat.

NewsCenter 5 and TheBostonChannel.com will have more details as they are available.