Students in Newtown, Connecticut, returned to school Tuesday, in the small northeastern town still reeling from one of the worst school shootings in U.S. history.

Schools opened two hours late as parents, educators and police hoped to resume some normalcy four days after a gunman opened fired at an elementary school, killing 20 students and six adults.

Classes are resuming at all the town's schools except Sandy Hook Elementary, where the attack occurred.

Town officials say counselors and police officers will be on hand as students and school administrators return. They also say plans are under way to relocate students who attended Sandy Hook to an unused school in the nearby town of Monroe.

Authorities believe the shooter, 20-year-old Adam Lanza, killed his mother at her home and then took her guns with him to the school. Lanza shot himself as police approached the school. Investigators say the motive for the shooting remains unclear.

Funerals are being held Tuesday for two six-year-old victims. The first two young victims, six-year-old boys, were laid to rest on Monday. More services are planned this week.

Mourners have placed stuffed animals, flowers, notes and papers angels outside the funeral homes and other locations in the town in tribute to the children, who were six and seven years old, and the adult victims.

All the adults killed were women and included the school's principal, who is reported to have tried to stop the shooter and a teacher who is credited with saving lives by putting herself between students and the attacker.

The horrific shootings have sparked yet another debate on gun control in the United States. Several Democratic Party lawmakers have called for a new push to restrict sales of guns and ban military-style assault weapons.

California Senator Dianne Feinstein, the author of an assault-weapons ban that lapsed in 2004, said she will introduce new legislation this week.

Friday's attack was the second-worst school shooting in U.S. history. The worst occurred in 2007, when a gunman killed 32 people at Virginia Polytechnic Institute and State University in Blacksburg, Virginia. Before that, the deadliest U.S. school shooting was the 1999 rampage at Columbine High School in Littleton, Colorado, where two teenagers killed 13 students and staff before killing themselves.