Students and staff at Montreal's Dawson College commemorated the most terrible day in their school's history, a shooting rampage that left one dead and 20 others wounded.

Hundreds gathered to hear tributes to students and police. Student Meaghan Blake sang a song chosen by the mother of shooting victim Anastasia De Sousa, killed by gunman Kimveer Gill on Sept. 13, 2006.

They held a moment of silence at 12:41 p.m. ET in the school's atrium -- the time when Gill began his shooting spree.

The troubled gunman took his own life after police shot him.

In the atrium ceremony, Richard Filion, the college's director-general, described De Sousa as a "joyous, happy, determined and strong girl."

The institution's students and staff have moved forward, he said.

"We stood up and were able to show that life is greater than destruction,"

Filion said, but added it's still difficult to comprehend why the shooting happened.

"The eruption of violence in a place of education such as ours is an absolute contradiction of what we represent. We still have no answers as to why this happened."

In a separate ceremony, the college planted a tree in memory of De Sousa.

The tree, which will blossom with pink flowers every spring, will be part of a peace garden.

"I honestly hope you will come, individually and collectively, to gather in the peace garden where we can rediscover the values ... of love, justice and peace," Montreal's Mayor Gerald Tremblay told attendees.

Student Ali Maynard had been at the school for about a month when the shooting happened.

A year later, "most of the students don't want to forget the incident, but they definitely want to move on from it and not deal with it any more," she told CTV Montreal on Thursday in advance of the ceremonies.

"This is a day of hope,'' Premier Jean Charest said after the tree planting. "This is a day that together we can look ahead.''

Charest described De Sousa as "an extraordinary young woman.''

The premier also thanked police, ambulance technicians and other personnel "who came to the rescue'' that day.

There were several rounds of cheers and warm applause for the Montreal police officers who risked their lives to take Gill down.

Anastasia's mother and father took a moment to thank the police officers who rushed in to stop Gill.

It was an emotional moment for the four officers who say their one regret is that they couldn't save Anastasia.

Over the past year, some of the students -- like Hayder Kadhim, who still has bullet fragments lodged in his skull -- have campaigned against gun violence and achieved some success.

Students cheered when Charest talked about the tabling of a law banning guns on campuses and public transit, which they named Anastasia's Law.

"Hopefully we'll be able to pass that legislation as fast as possible," he said.

The government also announced a $460,000 grant for a research project on the impact of the Dawson College shootings. The information gleaned from the study will help build a protocol for crisis situations in school settings.

With files from The Canadian Press and a report from CTV's Genevieve Beauchemin in Montreal