What constitutes a 4th Amendment seizure?

A 4th Amendment seizure occurs when an officer intentionally restricts another's freedom of movement. Brower v. City of Inyo, 489 U.S. 593, 596 (1989). The detention must be intentional because the 4th Amendment protects against misuse of power, "not the accidental effects of otherwise lawful government conduct." Id. In effecting a seizure, an officer's use of deadly force is reasonable only if "the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others." Tennessee v. Garner, 471 U.S. 1, 11 (1985).