'Don't focus on hate': World marks 20th anniversary of 9/11

9/11 - 20 years later

The world solemnly marked the 20th anniversary of 9/11 today, grieving lost lives and shattered American unity in commemorations that unfolded just weeks after the bloody end of the Afghanistan war that was launched in response to the terror attacks.

Victims' relatives and four U.S. presidents paid respects at the sites where hijacked planes killed nearly 3,000 people in the deadliest act of terrorism on American soil.

Others gathered for observances from Portland, Maine, to Guam, or for volunteer projects on what has become a day of service in the U.S. Foreign leaders expressed sympathy over an attack that happened in the U.S. but claimed victims from more than 90 countries.

"It felt like an evil specter had descended on our world, but it was also a time when many people acted above and beyond the ordinary," said Mike Low, whose daughter, Sara Low, was a flight attendant on the first plane that crashed.

"As we carry these 20 years forward, I find sustenance in a continuing appreciation for all of those who rose to be more than ordinary people," the father told those gathered at ground zero.

- with files from - Associated Press writers Michael Rubinkam in Shanksville, Pennsylvania; David Klepper in Providence, Rhode Island; Jill Colvin in New York; and Alexandra Jaffe in Shanksville and Washington contributed to this report.