DALLAS -- Visitors and media shouldering against a cold, grey, blustery day, began arriving at Dealey Plaza as early as 6 a.m. Friday for a spot at the ceremonies marking the 50th anniversary of the assassination of President Kennedy.

Streets were sealed off for several blocks in every direction and clusters of Dallas Police patrolled throughout the area, looking for any suspicious activity.

Despite the prospects of rain, umbrellas were banned for security reasons. Organizers instead handed out ponchos.

The event was by invitation only and some lucky 5,000 guests were selected in a lottery system.

Samuel and Tammy Ramon, of Fort Worth, applied in June and were thrilled when they were selected. Though he was only 1-year-old when Kennedy was shot, Samuel Ramon said being part of the 50th anniversary is something he'll someday tell his grandchildren and great-grandchildren about.

"He was a great president," said Samuel Ramon, bracing against the cold as he entered through security. "It makes me want to see where everything happened."

Roy Widley, 67, of the Dallas suburb of Richardson, also scored a lottery invitation to the event.

Standing a few yards from where the president was cut down by sniper Lee Harvey Oswald from a sixth-floor perch inside the Texas School Book Depository, Widley said he hoped the ceremony would, once and for all, distance Dallas from the killing.

"He was slain right here and the city's taken a lot of heat for that," he said. "A lone assassin killed the president, not Dallas."

The solemn, dignified mood at Dealey Plaza on Friday was in sharp contrast to the confusion and chaos that reigned 50 years ago as shots rang out and the presidential limo bolted forward to rush the stricken president to Parkland Hospital. A large white 'X" marks the spot where Kennedy was hit.

A large banner of JFK's portrait was erected as a backdrop for the main stage. Bells will toll throughout the city and a moment of silence will be observed at 12:30 p.m. CT, marking the moment when Kennedy was struck.

Many of the familiar sites from that tragic day are still here. Network cameras were set up at the Commerce Street plaza, opposite the grassy knoll, site of many assassination conspiracy theories.

The Coalition on Political Assassinations, which usually gathers on the knoll each Nov. 22, will not be allowed to meet at the site this year during the main event. Instead, The Dallas Morning News reports, the group will hold an event at the nearby JFK memorial, then move to the plaza after the ceremony is over.

A pre-event program was scheduled for 11:30 a.m. CT with music by the Dallas Symphony Orchestra.

The ceremony was organized as a joint event between The President John F. Kennedy Commemorative Foundation and the city of Dallas.

Mayor Mike Rawlings said it was "designed to set a solemn, dignified and understated tone as we commemorate the life, legacy and leadership" of President Kennedy.

The U.S. Naval Academy Men's Glee Club was scheduled to perform as a tribute to Kennedy's military service and there will be an Air Force "missing man" flyover.

The Bishop of the Catholic Diocese of Dallas was scheduled to offer the invocation followed by remarks by the mayor.

A live feed of the event was set up for viewing by the general public at three locations in and around downtown Dallas.

The nearby Sixth Floor Museum, which chronicles the assassination and is located on the same floor where Oswald fired on the motorcade, will open from 3 to 8 p.m. CT, after the formal ceremony.

Elsewhere in Dallas, a brief morning ceremony, including the lowering of a flag to half-staff, was scheduled at Parkland Hospital, where Kennedy died.

The Texas Theatre, where police captured Oswald, will screen part of the movie War Is Hell, which was showing when the assassin slipped into the audience without paying on the afternoon of Nov. 22, 1963.

Other events around the country:

In Washington, U.S. Attorney General Eric Holder paid his respect shortly after sunrise at Kennedy's grave at Arlington National Cemetery.In Hyannis, Mass., a wreath-laying ceremony was held at the John F. Kennedy Memorial in Veterans Memorial Park.

In Boston, the statute of John F. Kennedy was open for public viewing. A special mass commemorating the assassination anniversary was planend at Blessed Sacrament Chapel, Cathedral of the Holy Cross.