(CNN) More than 125 campers and adults who attended a summer camp run by a South Texas church have tested positive for coronavirus, according to a statement from Clear Creek Community Church Lead Pastor Bruce Wesley.
The outbreak stems from a late June Student Ministry Camp for sixth through 12th graders that was attended by more than 450 people, county health officials said.
"Unfortunately, upon return from camp, 125+ campers and adults reported to us that they tested positive for COVID-19. Additionally, hundreds more were exposed to COVID-19 at camp," Wesley said.
"And hundreds of others were likely exposed when infected people returned home from camp."
Clear Creek Community Church is an interdenominational church based in League City, with five campuses south of Houston.
The Galveston County Health District said it was notified of the first positive case tied to the church camp -- held at the Tejas Camp & Retreat in Giddings, outside the county -- on June 27.
At least three samples from the outbreak were confirmed to be the Delta coronavirus variant, which is more transmissible to others, according to the district. More samples are being tested.
"In this outbreak, at least as of now, it appears most of the people who have tested positive are old enough to be vaccinated. These vaccines are safe, effective and they offer the best protection against COVID-19 to you, your family and your community," Dr. Philip Keiser of the GCHD said in a statement.
Of 57 cases reported to the Galveston health authority, six people were breakthrough cases, the agency said, defining them as becoming infected more than 14 days after their second vaccination.
GCHD said 90 additional people, including those who don't live in Galveston, had self-reported their infections to the agency, saying there may be a lag in labs reporting results because of the Independence Day holiday.
"The health district is working closely with church leadership to investigate the outbreak, trace potential contacts and offer guidance and resources," health district officials said. "The youth group did not leave the campground during their stay. They did have contact with counselors from their church. No other campers were on site."
Tejas Camp & Retreat is monitoring its staff members' health and continues to use safety and testing as recommended by the state and the CDC, Executive Director Paul Biles told CNN on Tuesday.
Biles said Clear Creek Community Church was the only group using the facility when the outbreak occurred.
Services at all five of the church's campuses have been canceled through Wednesday, according to Wesley.
"From the beginning of the pandemic, we have sought to love our neighbors by practicing strict safety protocols. We are surprised and saddened by this turn of events. Our hearts break for those infected with the virus," Wesley said in his letter to the church community.
Health officials are asking anyone who attended the Clear Creek Community Church camp who either feels sick or is a "close contact" of someone who tested positive after attending the camp to get tested and quarantine at home while they await the test results.
"This is a reminder that COVID-19 is still here, and we have to take precautions," Keiser said in the county statement.
Some of those who tested positive after attending the camp were vaccinated against Covid-19, county officials said.