Edward Van Dyk, 43, tossed his two sons, ages 4 and 8, to their deaths around 8:20 a.m., Miami Beach Police spokesman Bobby Hernandez said. Authorities did not release the names of the two boys.
The mother of the children, Qinuo Van Dyk, 40, told police she and her husband had been having marital problems for the past six months, but hadn't argued right before the incident, Hernandez said.
The woman heard one of her children screaming from an adjacent room in the Loews Hotel, where the Alton, Ill., family was staying. When she walked into the room she saw her husband going off the balcony, Hernandez said.
She looked over the railing and saw her husband and her two children lying on a mezzanine roof that is about two floors above the ground.
Hernandez said that despite the marital problems, the family had been celebrating the couple's 10th wedding anniversary.
"It's a terrible tragedy. It's unfortunate that this gentleman was so selfish and in an effort to get back at his wife he took the two most loved people in the world away from her," Hernandez said.
Hernandez said the woman did not know why her husband, a radiation oncologist at Alton Memorial Hospital, killed the children and himself.
Edward Van Dyk began working at the hospital 18 months ago, when the family moved from New Mexico, hospital spokesman Rob Shelton said.
"We are shocked and saddened by this tragedy and we offer our deepest sympathy to Mrs. Van Dyk and her family," Shelton said.
People in neighboring rooms said they did not hear any noises, Hernandez said.
A Loews Hotel spokeswoman in Miami would not comment.