A young woman participates in the opening worship service of Winter Ramp at the Chattanooga Convention Center on Saturday night.

God brought 20-year-old Bryan Clem from northern Indiana to Chattanooga, he said.

"We heard that God is here strong -- you come here and you're guaranteed to be rocked," he said, swaying to the music as the first service of the 11th annual Winter Ramp -- a conference that offers three days of Christian worship, teaching and music to young people -- kicked off.

Clem made the nine-hour drive with other people from his church and said he didn't think twice about paying the $50 early registration fee.

"It's God," he said, and shrugged. "I'd do anything."

About 4,500 mostly high school and college students are expected to attend this weekend's events, said Joe Reeser, chief operating officer for the Ramp.

"The primary purpose in the gathering is to provide an environment and an atmosphere where young people can experience the presence of God," he said. "And also that they go home with a sense of deep purpose: That they can give their lives for something that has eternal results."

During Saturday night's service, students gathered to sing and dance. Some people swayed slowly to the music; some raised their hands and closed their eyes. Others danced and jumped, shouting, clapping and waving their arms.

The room at the Chattanooga Convention Center was set up concert-style, with a raised stage in front, sweeping cameras, two screens showing live shots of the service and brightly colored flashing lights. The music boomed through the sound system.

"Right now I feel like something big is going to happen, not just in Chattanooga but across the nation," 15-year-old Blake Davis said as the service began.

He attended Winter Ramp last year and felt so good about the weekend he decided to make the five-hour trip from North Carolina again this year.

"I wasn't expecting what happened last time," he said. "It was a great thing. I just want to get filled and connected to God more."

Blake plans to stay for all seven services. He hopes to become a missionary in Belize after he graduates from high school.

"I went there for my first missions trip, and I just felt like God wanted me there for a reason," he said.

This year's Winter Ramp is once again being held in Chattanooga after being hosted in Dalton, Ga., last year.

"We're excited to be back in Chattanooga," Reeser said. "It's a city that's really perfectly suited for this kind of thing."

Last time the event was in Chattanooga, in 2010, the Chattanooga Convention and Visitors Bureau estimated it had an economic impact of $2.7 million for the city.

Tim Rios, the father of a 16-year-old, said he brought his family to Winter Ramp after attending and enjoying a similar event in Hamilton, Ala., where the organization is based.

As the service kicked off Saturday, he tried to explain why he returned.

"Well," he said, "it was just a touch of God."