Some 80 searchers spent Monday working their way through the swampy backcountry of Congaree National Park in search of a father and his two young children who were reported missing nearly 48 hours earlier.

But at the end of the day no sign of Jerry Robert Kimbler, 43, of Lexington County, South Carolina, and his children, 10-year-old Dakota and 6-year-old Jade, had turned up, the National Park Service reported. The search was to resume at first light Tuesday in the park, which was otherwise closed to the general public.

The three were reported missing Saturday evening by the children's mother. Apparently Mr. Kimbler sent a text message asking for help at about 9:30 p.m. Saturday to a friend. The three were believed to have gone down a trail near the park's Harry Hampton Visitor Center.

Rangers conducted a "hasty search" of the nearby trails with local search and rescue partners before calling it a night and resuming their efforts Sunday morning. By Monday more than 65 trained search and rescue personnel and 15 volunteers had searched approximately 9,000 acres of the 27,000-acre park.

The ground crews were aided by fixed-wing aircraft and helicopters using thermal imaging and night visioning sensing technology. Ground crews utilized canine tracking teams and and conducted off-trail searches by boat. The search has been difficult due to a winter ice storm that left numerous downed trees obscuring trails along with high waters and dense vegetation, park personnel said.

Rangers do not believe the party were prepared for a backcountry stay. Weather conditions have been mild, but rain and storms are expected later this week.