OTTAWA - Prime Minister Stephen Harper said he had to turn the TV off last weekend because it became too tough to watch coverage of the Newtown school massacre.

"It's almost impossible to imagine how someone could do something like that to children," he said in an interview Tuesday with QMI Agency's Pierre Bruneau.

"It's a massive tragedy."

Last Friday, gunman Adam Lanza walked into Sandy Hook Elementary School in Newtown, Conn., and killed 20 children and six adults.

The violence has renewed debate over gun control in the U.S., but Harper said Canada's gun laws are more strict.

"We won't change the foundation of our system," he said. "We abandoned the gun registry because it was costly and - according to us -- had no benefit."

Harper said the Conservatives would keep permits for gun owners and other measures in place.

"We're keeping a system that works, and that's key - having a system that works," he said.