(ABC 7 Chicago)

Rescuers using heavy equipment pulled a young boy from a hole in a large sand dune on an off-limits area of an Indiana beach after more than three hours, officials said.

The boy, 6, appeared to have vital signs upon being pulled out but his exact condition remained unknown, Bruce Rowe of the National Park Service said late Friday.

After the rescue, the boy was taken to St. Anthony Hospital in Michigan City, Mich., before being taken via helicopter to another hospital in the Chicago area, Michigan City Fire Chief Ronnie Martin told ABC News.

Some officials initially gave the boy's age as 8.

The boy was walking with his parents along the sand dunes by Lake Michigan from near Mount Baldy, Martin said, when he came across a rotted tree that may have caused some type of sinkhole in the sand dune.

The area where the boy fell was off limits to the public, Rowe said.

The call for help went out at approximately 4:30 p.m. CT, officials said. Rowe said local first responders arrived within about 15 minutes.

Those responders included medical personnel, the Michigan City Fire Department and Michigan City police, Martin said.

As they were digging, the hole became larger, so they called in heavy equipment in to move the sand, Martin added.

Fire department rescuers said that as they were digging they found a soft spot or pocket in the sand and saw the boy's head.

Rescuers were able to lift him out at approximately 8:05 p.m. CT, Martin said.

ABC News' Ben Stein and Michael Howard contributed to this report.