The school has reached out to families to advise those affected that support is available.

It follows the discovery of an adult woman and two male children in the Gungahlin lake on the weekend.

The eight-year-old boy has been identified as Pranav Vivekanandan, a student at Harrison School.

Executive principal Andy Mison said the school was focused on looking after each other, its staff, students and community.

"It's a tragic event," Mr Mison told The Canberra Times on Monday.

In a letter to families on Sunday night, the school advised that two of their students and a parent had died on the weekend.

"Today and over the coming weeks, you may be concerned about your child's reaction or expression of feelings about this news," the letter said.

"These reactions and feelings may be part of the grieving process.

The letter said many students will wish to talk with their family about the incident. Resources were provided to assist parents in having that conversation.

"I also encourage you to let your child know that you're aware of this incident and that you'll listen to their concerns at any time they wish to share them.

"Staying connected and engaged with your child is one of the best ways to support them.

"Our classroom teachers will advise our students of this using age-appropriate concepts and language during the first session."

Pranav's body was pulled from the water about 10.45am on Sunday, following a search of the lake involving about 30 police officers, divers and a drone operator.

The bodies of his mother and brother were discovered on Saturday morning.

Police do not believe another party was involved in the incident.

Pranav's father lives in Canberra.

Police have not published the names of the mother and young boy.

READ ALSO:

An investigation was launched into the three deaths on the weekend.