Prime Minister Jean Chretien says he's horrified by the attacks, and called those responsible "cowardly" and "depraved."

"It is impossible to fully comprehend the evil that would have conjured up such a cowardly and depraved assault upon thousands of innocent people ... indeed, such an attack is an assault not only on the targets but an offense against the freedom and rights of all civilized nations," says Chretien.

Chretien says he's told the U.S. that Canada will do everything it can to help the victims of the attacks, and he adds he's been in touch with the Canadian ambassador in Washington, D.C.

When asked if there's any evidence Canada was used by the attackers before the crashes, Chretien responded, "we don't have any evidence."

All cabinet ministers have been called back to Ottawa, and the prime minister has cancelled all appointments Tuesday.

"I've been in touch with ministers and the head of the RCMP and Armed Forces all morning," says Chretien.

"I'm not going to Halifax today, I was supposed to be in Halifax at this moment ... and there will be no official meeting with the president of Slovakia that was supposed to be in Canada tomorrow," says Chretien.