About a hundred students demonstrated outside a Tucson high school Tuesday, then marched five miles downtown to protest the arrest and removal to Mexico of a classmate and his family.

The students apparently did not walk out of classes but arrived at Catalina High School on ready to demonstrate and head to the federal building, Tucson Unified School District spokeswoman Chryl Hill Lander said.

Tucson police spokesman Sgt. Mark Robinson said at least some of the demonstrators veered off to congregate peacefully outside police headquarters.

One erroneous rumor of a Border Patrol raid started circulating at the time of Thursday's removal of a ninth grader, authorities said.

"We heard rumors that it was a raid by Border Patrol, which it was not," Lander said.

School officials searched the backpack of a 17-year-old freshman who was incoherent, and when they found a substance that looked like marijuana, called police — standard procedure.

"Police were called in because there was marijuana found in a student's backpack," Lander said. "Administrators have the right to go through a backpack when the situation warrants, and the student was acting strangely, was incoherent. He wasn't able to talk and make complete sentences," she said.

Police called the boy's parents and asked them to come to the school. When they arrived, police asked to see their drivers' licenses.

The parents acknowledged living in the United States illegally with their two sons, including a sixth-grader, for a half-dozen years.

Police in turn notified the Border Patrol, who took all four people into custody.

Immigrants rights activists voiced concern about the incident, but Tucson police defended calling the Border Patrol as the appropriate action.

Jennifer Allen, director of the Border Action Network, said allowing immigration agents into schools could create more mistrust and fear in the immigrant community.

But assistant police chief Roberto Villasenor said, "An administrator came across a juvenile who was violating the law, in possession of marijuana. That is a crime in this country, whether you are here illegally or not."

He added that his department does not want its officers to become immigration agents but that they will call federal agents when they believe it's required.

The mother and boys were agreed to be returned to Mexico on Thursday and the father was ordered removed. He was sent back to Mexico the next day, Border Patrol spokesman Richard DeWitt said.

The father had been caught entering the country illegally several times, DeWitt said.

"We would have preferred that they took him off-campus" to complete the family's removal, Lander said.

"We have requested a meeting with the Tucson Police Department to discuss how a situation similar to what happened at Catalina last Thursday will be handled; because we don't think that school campuses are a proper venue for immigration issues to be resolved."

"We don't enter onto school or church property without invitation or unless for emergency situations," DeWitt said. "In this instance, we were requested to assist by the Tucson Police Department and our assumption was that the school administration was aware of the ongoing situation."

Lander said the students who took part in Tuesday's protest would be granted excused absences if their parents notify the school their child had permission to be absent.