BOSTON (AP) - State police have arrested 21 people who refused to leave the state Department of Transportation offices in Boston, where they were protesting.

Authorities arrested 11 women and 10 men around 7 p.m. Monday and charged them with trespassing. They say the protesters had discussed their concerns with transportation officials but would not leave the offices more than two hours after they closed. Most of those arrested were young adults.

The alternative newsweekly DigBoston reports that activists staged the protest to seek a more affordable ridership program for young people.

State police say protesters without outstanding warrants will be released on $40 bail. They will appear in Boston Municipal Court sometime in the future.