Allison Pressman, 15, arrived at the King of Prussia Mall at 5:30 this morning along with three of her closest friends.

Pressman was horrified. More than 500 fans were already standing in line. She was 17 hours too late.

Mall security turned Pressman away - along with at least 300 others.

"I thought it was a joke," said Pressman, of Palmyra, N.J. "I wanted to cry."

Hundreds had stood in line since it formed late Wednesday night. Each hoped to snag a numbered wristband that would allow them to meet rising teen idol Robert Pattinson, star of the upcoming vampire flick, Twilight, later today.

Fans began arriving just after noon Wednesday and camped out overnight in the mall parking lot.

A disappointed Pressman watched the dawn rise from a heated bus shelter with her sister, Nikki, 16, and friends, Mary Brennan, 15, and Elise Brennan, 16, of Havertown, Pa.

But they had no plans to leave King of Prussia.

The quartet planned to stay at the mall until tonight when Pattinson is scheduled to hold a 9 p.m. question and answer session in the courtyard area of the former Strawbridge's.

"I'm planning on being first in line for that," said Pressman.

The multitude of Twilight fans - and their parents - endured rain and bone-chilling temperatures last night so they could shell out $30 for a Twilight t-shirt that was packaged with the wristband. The wristband entitles the wearer to meet Pattinson, who plays an elegant English vampire who falls in love with a shy American girl.

Pattinson's appearance today at the Hot Topic store is the fourth scheduled stop of a nationwide blitz to promote the film, which doesn't open until Nov. 21. The movie is based on Stephanie Meyer's four Twilight vampire novels, which have sold 17 million copies worldwide.

Kelly Maguire, 16, from Wilmington, Del., was No. 251. She could have purchased two t-shirts and been awarded two of the paper wristbands to meet Pattinson. But she only bought one.

"There's people in line in back and if I bought two that might mean they couldn't get in," said Maguire. "I'd cry if that were me."

Maguire said mall security initially told the throng they couldn't queue up until midnight.

"They lied!" said Maguire, a high school sophomore. "At 9:30 p.m we found out they changed it. We were at TGI Friday's about to eat. We canceled our orders and ran through the parking lot."

A spokesman for the mall this morning said that Upper Merion police asked for a change in plans to avoid a mad dash and eliminate the chance of a stampede.

Maguire, who plans to shop all day at the mall until she meets Pattinson, said the crowd could have been a lot bigger.

"There would have been 10,000 people here if there wasn't such a thing as school," she said.

The planned appearance of Pattinson, 19, in a San Francisco mall on Sunday caused a near riot, forcing the signing to be canceled.

In King of Prussia this morning, the mall was taking no chances. A small army of security officers and police - at least 30 - made certain the crowd was well ordered.

Fans hoping to meet Pattinson in person and get an autograph began arriving at the mall at 12:30 p.m. Wednesday - some from as far away as Buffalo, N.Y. and Cary, N.C.

Anyone who arrived after 10 p.m. Wednesday were out of luck. Security counted off 500 fans at midnight and broke the bad news to the rest of the line, which snaked around the mall.

"A lot of people started crying," said No. 500, Jessica Franklin, 16, of Mount Airy and a sophomore at Central High School.

Franklin, accompanied by her father Courtney Franklin and two friends, said she planned to stay until Pattinson's late night Q&A is over.

At the front of the line, clutching a red voucher scrawled with No. 1, stood aspiring actress Daria Rose, 23, of Broomall.

Rose arrived at 12:30 p.m. Wednesday and immediately put together a game plan to ensure she'd get in. She chatted up the sales clerks at Hot Topic, talked to mall security, and searched for the entrance where the line would form.

"It was very Willy Wonka-ish," she said.

Rose said she and a group of other early arrivals helped to organize the line.

"We wanted it calm and orderly," Rose said. "We didn't want people to get hurt like in San Francisco."

Rose said she teaches drama at Archbishop Ryan in Radnor, one of three jobs she holds.

"One of my students brought the book in for me to read," she said. "Since then I haven't been able to put them down."

Right behind Rose was Christina Toth, 31, of Horsham, who stood shivering with her 14-year-old daughter, Dezerae Haines. The pair arrived at 1 p.m. Wednesday.

It wasn't the first time Toth had camped out for a special event.

"I sat out at Christmas time for the Furby (top selling toy), remember that? It was an overnighter too," said Toth of her long-line resume.

Overnight, Toth dozed in her car while Dezerae, a freshman at Hatboro-Horsham High School, "was on the cold ground, crushed like a sardine."

Dezerae said she cat-napped for about a half hour after lining up "officially" at 9:30 p.m.

The Hot Topic stop provided pizza, hot coffee, and water to the chilled fans who camped out overnight outside the mall, Dezerae said.

As TV lights lit up portions of the line, the crowd erupted into joyous shrieks and cheers.

A publicist for Twilight said the actors appearance at King of Prussia cost a small fortune. But he called the resulting media exposure "invaluable."

"All these screams - you can't put a price on that," he said.