NEW YORK (AP) - Grieving siblings of those who died at the World Trade Center returned to the site on the fourth anniversary of the nation's worst terrorist attack, promising their dead brothers and sisters they would never be forgotten.

''My big sister, my better half, life will never be the same without you,'' Rolando Moreno said to Yvette Moreno, who died in Sept. 11 attacks.

More than 600 siblings on Sunday read aloud the names of the 2,749 victims who died at the complex four years ago. Thousands of relatives held pictures of their loved ones aloft, while others carried flowers. Some sobbed during the four-hour ceremony.

The mourners paused for moments of silence at 8:46 a.m., the time when the first hijacked jetliner crashed into the north tower; at 9:03 a.m., when the second plane struck the south tower; at 9:59 a.m., when the south tower fell; and at 10:29 a.m., when the second tower collapsed.

''You were my baby brother, I took care of you,'' Iliana Flores told her paramedic brother, Carlos Lillo, as she choked up and raised her face to the sky. ''I still miss you a lot. You're taking care of us from heaven but someday we'll be together.''

Tears sometimes swallowed their words as they read the names, and relatives in the crowd bowed their heads and cried as the siblings spoke. Several times, the brothers and sisters came in groups - sometimes six or seven large - to honor their loved one, all huddling together to say the name. Some blew kisses to the sunny, pale-blue sky, while others said over and over, ''We love you. We miss you.''

''We know you're keeping everyone laughing up in heaven,'' said Kathleen Pslrogianes to her brother, Thomas Cahill, a Cantor Fitzgerald trader who was 36 when he died.

As the names of the dead were read, weeping mourners filed down a ramp to a reflecting memorial pool at the floor of the site, which remains virtually empty four years after the attack tore a hole in the New York skyline.

Families filled the water with red, orange and yellow roses, some shaking as they inscribed dedications on the wooden edge of the pool.

''We miss you Charlie and we love you, your boys will always remember,'' Peggy Garbarini told her brother, Fire Lt. Charles William Garbarini.

Parents and grandparents read the victims' names at ground zero last year, while children's voices were heard in 2003. A selection of politicians, relatives and others read the names on the first anniversary.

New York Mayor Michael Bloomberg opened the ceremony with words of condolence for those devastated by Hurricane Katrina and the July terrorist bombings in the London Underground.