Red Lake, Minn. ? More than two-thirds of the students stayed away Tuesday as Red Lake High reopened for the first time since a teen gunman killed seven people at the school.

Some people were worried about another attack, said Pat Mills, public safety director for the Red Lake Band of Chippewa.

“It’s a fear that goes through everybody’s mind,” Mills said.

Sophomore Tom Barrett was among the small group of students who attended classes at the school, located on the tribe’s reservation.

“I think it’s the perfect time to go back,” he told reporters across the street from the school. “We have to be there for each other as a nation.”

Journalists weren’t allowed on the school grounds.

Jeff Weise, 16, described as a loner and admirer of Adolf Hitler, killed his grandfather and the man’s girlfriend, then went to his school and killed five students, a teacher and an unarmed security guard. He then committed suicide.

The shootings remain under investigation, and a 16-year-old boy, Louis Jourdain, has been arrested as a possible accomplice. Tribal chairman Floyd Jourdain Jr. has maintained his son is innocent.

Other students in the district reportedly have been subpoenaed. Paul McCabe, an FBI spokesman in Minneapolis, said he couldn’t comment on the investigation.

However, a federal law enforcement source with knowledge of the case told The Associated Press on Tuesday that investigators were looking at two groups: A coconspirator group of up to nine people, and a larger group of people who may have had some prior knowledge of an attack because Weise talked about it.