Many people gathered in a room with several people on stage with instruments and the words 'The Early November' on the wall.
Parents gathers for a local high school concert
People gathered in a room does not imply that they are parents. People on stage with instruments does not imply that it is a concert, or that it is held at a local high school.
Venue may not be school concert the people may not be parents
The people aren't necessarily parents there for a high school concert.