Mr. Baena, who was married to the actress Aubrey Plaza, co-wrote the existential comedy “I Heart Huckabees,” and wrote and directed films including “Life After Beth” and “The Little Hours.”

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Mr. Osmond was a founding member of the family pop group, which had a slew of hits in the 1970s, including “One Bad Apple” and “Yo-Yo.”

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At least seven people were injured, the authorities said. They said they believed it to be “an isolated incident,” but had not ruled out a connection to the attack in New Orleans.