RED LAKE, Minn. (AP) – Authorities who had received a tip that a gun had been stashed at the site of a deadly school shooting said Friday they found no such weapon in their latest search.

“There was nothing found out of the ordinary” when about 30 FBI and tribal officers searched Red Lake High School on Thursday, said Pat Mills, public safety director for the Red Lake Band of Ojibwe.

U.S. Attorney Tom Heffelfinger would not disclose what caused authorities to believe there was a gun in the building on the Red Lake Indian reservation. He told the Star Tribune of Minneapolis that nothing “would indicate that anybody infiltrated that building after March 21 and planted anything.”

The school has been closed since March 21, when 16-year-old Jeff Weise killed five students, a teacher and a security guard before shooting himself.

Weise headed to the school after killing his grandfather and the man’s girlfriend on the reservation.

Louis Jourdain, the 16-year-old son of the tribal chairman, has been arrested as a possible accomplice.

Classes were delayed an additional day because of the search and were to resume Tuesday in an old section of the high school. The shootings happened in a new addition to the building.

The elementary and middle schools were to reopen Monday, when school officials plan a healing ceremony at the high school.

The first day of classes will be light on academics, and students at the middle and high schools will be on a half-day schedule for the first week, said Jean Whitefeather, the principal at Red Lake Elementary School and acting superintendent on Friday.

Students won’t use the main doors Weise walked through during his killing spree. Every classroom on the reservation will be locked, and armed Bureau of Indian Affairs officers will patrol the hallways.

Although officials expect many students will stay home, “A school is a family, and they’ve been missing part of their family,” Whitefeather said.

Student Michael Jourdain on Friday was thinking about the classroom where most of the killings took place, and about his slain cousin, security guard Derrick Brun. But the 18-year-old also was thinking about resuming normal school life: getting his diploma and taking a girl to the prom.

“It’s going to be hard to look at all that, especially that room where all the kids died,” said Jourdain, who also is a cousin of Louis Jourdain. But he added, “I’m ready. I need to get stuff done in school.”