The three men were previously questioned in the disappearance of Natalee Holloway, 18, and described as "persons of interest." They told police they dropped off Holloway, of Mountain Brook, Ala., at her hotel early May 30, but Holiday Inn employees say security cameras did not record her return.
Police also impounded a gray Honda car. Holloway's friends reported seeing her leave a nightclub in a silver car the night she disappeared.
Attorney General Caren Janssen said the three were arrested at 6 a.m. She refused to identify them, but authorities previously described them as students — two Surinamese brothers and the son of a Dutch justice official studying to be a judge.
The Dutch suspect, Joran Andreas Petrus Van Der Sloot, a student at Aruba International School, came out of his upper-class home in the northern Montana neighborhood of Oranjestad on Thursday with his head covered in a blue-and-green towel.
The other two suspects, identified as Surinamese brothers Satish and Deepak Kaploe, told police Natalee had been drinking and fell down as she got of the car in front of the hotel, a source close to the investigation told The Associated Press on condition of anonymity.
When Van Der Sloot tried to help her, she refused, saying, "I can stand on my own," the source said.
At that moment, the Surinamese brothers told police, a black man dressed in a black security uniform and carrying a Walkie-Talkie went up to Natalee, seemingly to offer his assistance. The suspects then drove off, and did not see Natalie again, they told police, according to the source.
The attorney general's office had said previously the three were considered witnesses and not suspects.
Janssen refused to say whether the three were connected to two men previously detained in Holloway's disappearance, saying more information would be released later Thursday. A judge ruled Wednesday there was sufficient cause to keep holding the two former hotel security guards.
The decision means authorities may detain Nick John, 30, and Abraham Jones, 28, for nearly four months while prosecutors investigate possible murder and kidnapping charges, defense attorneys said. Neither man has been formally charged.