To add to the discussion from findlaw - what really matters is the 4th Amend, not what some newspaper or Press Release wants to call it. It is an arrest.
A Fourth Amendment ''seizure'' of the person, the Court determined, is the same as a common law arrest; there must be either application of physical force (or the laying on of hands), or submission to the assertion of authority.
sourced from these cases
The Fourth Amendment applies to all seizures of the person, including seizures that involve only a brief detention short of traditional arrest. Davis v. Mississippi, 394 U.S. 721 (1969); Terry v. Ohio, 392 U.S. 1, 16 -19 (1968). "[W]henever a police officer accosts an individual and restrains his freedom to walk away, he has `seized' that person," id., at 16, and the Fourth Amendment requires that the seizure be "reasonable." As with other categories of police action subject to Fourth Amendment constraints, the reasonableness of such seizures depends on a balance between the public interest and the individual's right to personal security free from arbitrary interference by law officers. Id., at 20-21; Camara v. Municipal Court, 387 U.S. 523, 536 -537 (1967).