BROOKLYN - Students at John Dewey High School were met Friday with increased security and metal detectors after a gun on campus triggered a lockdown.No students were allowed on or off the campus during the lockdown Thursday while police searched for the gunman. Police say no weapon has been recovered yet and no arrests have been made.An increase of police and patrol cars around school grounds had some students questioning the future policies of the high school.School officials say they do not have plans to permanently install metal detectors despite parent?s demands. Gun slipup prompts Gravesend high school lockdown