A hatchet-wielding man who charged at four rookie New York City police officers on Thursday as they posed for a photograph on a Queens street was shot and killed after he struck one of the officers in the head and another in the arm, William J. Bratton, the police commissioner, said.

Stray police bullets also struck a 29-year-old woman in the lower back as she walked in the rain about half a block away along a normally crowded commercial stretch of Jamaica Avenue just after 2 p.m.

The man, who was not immediately identified by the police and whose motive for the attack remained unclear, died at the scene. The police recovered a blue-handled, 18-inch hatchet, and Mr. Bratton displayed a photograph of the weapon at a news conference at Jamaica Hospital Medical Center on Thursday evening.

“At this point, no known motive for this attack has been established,” Mr. Bratton said.

Kenneth Healey, a 25-year-old recent graduate of the Police Academy, was in critical but stable condition after suffering a “very serious injury to the backside of his head,” Mr. Bratton said. The officer struck in the arm, Joseph Meeker, 24, was expected to be released.