State police in Brazil say an American couple and their two daughters have been missing since Sunday, when river pirates assaulted the boat taking them and other passengers to an island on the Amazon River delta.

The Para state Public Safety Department says a search is underway for the missing family.

It said Tuesday that pirates forced the boat to dock and fled with the belongings they stole. When police, arrived the Americans were not on the boat.

It identified the couple as Adam Harris Heart, 39, Emily Faith Heart, 37 and their daughters aged 3 and 7. The children's names were not revealed.

The department says the family lived in the southern city of Florianopolis.

More details were not immediately available. The U.S. Embassy had no immediate comment.