Downtown hotels, Hart Plaza, Cobo Center and Ford Field are jammed with ebullient teens and harried chaperones who add a theme park vibe.

They arrived Wednesday for an Evangelical Lutheran Church in America Youth Gathering -- five days of faith, festivities and public service. The event has nearly 30,000 participants and "is expected to bring a $30 million economic impact to the region," Sherri Welch blogs at Crain's.

“This place is going to look like Disney World for a few days,” Michael O’Callaghan of the Detroit Metro Convention & Visitors Bureau tells her.

He refers to hundreds of tour buses, but the comparison also is apt because of matching T-shirts, outdoor snacking, selfie snapping and the type of effusive enthusiasm this tweet reflects:

Detroit watch out! CRAZY FOR JESUS! Waiting 3 years for this!!!! This is going to be an amazing week!!#RiseUpELCA pic.twitter.com/4jGxhE3lCb — Emily Martinez (@em_m1021) July 16, 2015

Downtown worker Diana Thomas McNary, a Detroit News graphic artist and designer, comments on her Facebook page: "They've really changed the downtown vibe from 'too-cool-for-you hipster' to 'yayyyy wheeeee OMG where are you from???' "

Updates: Jason Marker, a member of the Detroit Party Marching Band, posts on our Facebook page: "They are insufferably cheerful."

Another reader, Colleen Hasten of Grosse Pointe, comments: "It looks like a Skittles factory exploded."

The national event isn't all prayers, speeches and selfies, Welch notes Thursday:

Today through Saturday, 10,000 high school-aged kids and adults will board 220 buses each day at Hart Plaza and head to nonprofits around the city, in Highland Park and Inkster to take part in community service projects. Those projects -- 600 in all -- will focus on providing housing and food, education, environmental sustainability, arts and culture, and other services. About 100 area nonprofits will benefit from the volunteering, the Detroit Metro Convention & Visitors Bureau said.

Beneficiaries include the Belle Isle Conservancy, Focus: HOPE, Detroit Public Library main branch, Cass Community Social Services and Gleaners Community Food Bank of Southeastern Michigan, the Crain's writer adds.

This is among Thursday morning tweets as volunteers headed to the nonprofits:

And in a decidedly deeper tone, this was posted from Cobo on opening night: