A 33-year-old mother climbed over a safety rail and intentionally went over Niagara Falls with her two children, a nine-year-old and five-month-old, according to New York state police.
Officers said on Wednesday that search and rescue efforts were unsuccessful.
Authorities responded to the park at about 9pm on Monday and determined the family went over the rail on Luna Island, a small island between the American Falls and Bridal Veil Falls that, along with the Horseshoe Falls, make up the popular tourist attraction.
“The investigation has determined that this incident was intentional in nature, though the circumstances remain under investigation,” state police said in a statement.
Authorities are using unmanned aircraft and underwater units in the investigation.