Sergeant Sean Kooistra says the 12-year-old girl and her nine-year-old brother were in the park around 3:15 PM when they noticed a man was following them.

Kooistra says the children took different paths but the man kept following them, so they ran until they saw a construction worker at a nearby home:

Kooistra says the man is a white male, possibly 50 to 55 years old, six-feet-two and slender, with a weathered, wrinkled face. He was wearing a green jacket, described as "poofy," a red or brown baseball cap and a backpack, and riding a blue or black mountain bike.

Anyone who may have information is asked to contact Sioux Falls Police or Crimestoppers.