NEWTOWN, Conn. -- Sandy Hook Elementary School, the site of the second deadliest mass shooting in U.S. history, will remain closed for the next several months, police said early Monday, and school officials don't know if it will ever open again.

Public schools across Newtown plan to reopen their doors Tuesday, local authorities indicated, but police are holding Sandy Hooks as a crime scene "indefinitely," said Lt. Paul Vance of the Connecticut State Police.

Police also seized the house shared by the shooter, Adam Lanza, and his mother, Nancy Lanza, the first victim in the mass shooting who police found dead in the home.

"We've seized it under search warrants and we're going to hold those locations until we've completed our work and believe it's appropriate to let those locations go," Vance said.

Even after police release the school building, it's unclear what will happen to it.

"At that point it's up to town officials to determine what's appropriate for that facility," Vance said.

Children who attend Sandy Hooks will transfer to another school in a nearby town later in the week.

"The schools are working very closely with all the faculty, students and parents to try to be respectful and try to resume what normalcy we can after a tragedy such as this," Newtown Police Lt. George Sinko said.

As some in this quiet New England town attempt to return to their daily lives, the families of the victim are preparing to bury their lost loved ones. Funerals for Noah Pozner and Jack Pinto, two of the 20 children shot and killed by Lanza on Friday, will be held Monday afternoon.

Schools elsewhere around the state resumed classes, but remain on edge with heightened security and continuing threats. A student was charged with making a threat at a high school in Bristol, Conn., Sunday evening and schools in nearby Ridgefield were locked down Monday morning after a suspicious person was spotted at the Branchville train station.

Vance warned that any threats made on the Newtown community will be thoroughly investigated and charges will be sought.

Police have yet to release a motive for why Lanza forced his way into Sandy Hooks Friday around 9:30 a.m., shooting and killing 26 students and staff. There was no previous contact with police or any prior concerns, Vance said.

They are optimistic that the evidence they have obtained so far will, however, provide greater clarity. Investigators are checking all local gun ranges, gun stores and databases for further information and analyzing electronics found in Lanza's home.

Police spoke already with two adult survivors and in the coming weeks will interview the children who witnessed the attack.

"It's a very, very tender issue," Vance said. "And I can tell you that any interviews with any children will be done with professionals, with parents and with investigators as appropriate. The investigators will determine how, when and where that is appropriate."