BALTIMORE —  Supporters of perennial presidential candidate Lyndon LaRouche (search) and other hecklers interrupted Tuesday's Democratic debate at Morgan State University (search) and university police arrested four people.

"Where's LaRouche?" shouted one woman during remarks by Sen. Joe Lieberman (search). There were at least five interruptions during the 90-minute debate.

Debra Freeman, national spokeswoman for LaRouche, said supporters disrupted the debate because LaRouche was not allowed to participate.

University police arrested four people, although officers simply escorted others out of the building, said Detective Donny Moses, a Baltimore police spokesman.

Morgan State, a historically black university, was the site of the debate co-sponsored by the Congressional Black Caucus and the Fox News Channel.

"This is a historic occasion -- the first time that the CBC has hosted a debate at an HBCU," candidate Al Sharpton said after one interruption. "Will you respect our time the way we respected yours?"

"Do they do that to Republicans?" asked former Illinois Sen. Carol Moseley Braun.