As the search for Jayme Closs stretched into its seventh day, the Barron (Wis.) County Sheriff's Office said Sunday that it's investigated more than 1,000 tips since the 13-year-old went missing from her home last Monday.

"Jayme remains missing and endangered and has been added to the top of the FBI's Missing Persons list, and is currently on digital billboards nationwide," Sheriff Chris Fitzgerald said in a statement posted on the agency's Facebook page.

Authorities say that Closs was in the family's house outside of Barron early Monday when her parents, James and Denise Closs, were fatally shot. The teenager has not been seen since.

The Sheriff's Office is holding a news briefing at 4 p.m. Monday. A "gathering of hope" for Closs is scheduled for Monday night at Riverview Middle School. There, the Barron Area School District plans to provide residents with resources and crisis support for dealing with the trauma of Closs' disappearance.

In his statement, Fitzgerald wrote: "Thank you to all of our law enforcement partners, citizens and businesses of our community for your continued support and prayers to bring Jayme safely home."

Anyone with information is asked to call a 24-hour tip line, 1-855-744-3879, or to e-mail jaymetips@co.barron.wi.us.