In a 42 U.S.C. section 1983 action in which plaintiffs alleged that a police officer used excessive force when he fatally shot plaintiff during an attempted arrest, the district court's grant of summary judgment to defendants is reversed where summary judgment is not appropriate in section 1983 deadly force cases that turn on the officer's credibility that is genuinely in doubt; and 2) the version of events offered by the officers to the district court was materially contradicted by evidence in the record.