By AMANDA ANDRIES, JANET DIGERONIMO & SEAN QUIGLEY

The Port Authority of New York and New Jersey held a solemn ceremony at the 9/11 Memorial on Tuesday, marking the 20th anniversary of the first attack on the World Trade Center in which six persons died and more than 1000 were injured.

Four of the six killed were Port Authority workers.

A church service at St. Peter’s Roman Catholic Church preceded the outdoor event.

“Like you I’ve shed tears over the last twenty years,” reflected former mayor David Dinkins who occupied City Hall at the time of the terrorist attack which foreshadowed a much more serious one on the same site eight years later. “Nothing prepared me for the profound magnitude of suffering”

Current mayor Michael Bloomberg also attended both events.

At 12:18 p.m., on that fateful day, a truck packed with over 1500 pounds of explosives blew up in the underground garage of the North Tower. At that same time today, a bell rang and a moment of silence was observed.

Michael Macko was 29 when his father William, air jordan 7 a Port Authority worker, was killed in the attack.

“It’s important to remember now that we have this beautiful memorial, but it’s important to remember what happened as well,” Macko said.

Decked out in full Irish costume and playing bagpipes, The Emerald Society of the NYPD slowly marched past the North Pool of the memorial. Family members then placed white roses on the granite surface, into which the names of the victims are etched.

Six Islamic extremists were arrested and convicted for planning and carrying out the attack.

The National September 11 Memorial and Museum, which is slated to open in 2014, will feature the 1993 bombing prominently as a part of its installations.