HONG KONG — Ringo Lam, a Hong Kong film director best known for gritty crime thrillers like the 1987 classic “City on Fire,” died on Dec. 29 at his home in Hong Kong. He was 63.

The police confirmed Mr. Lam’s death. The cause was unknown, the police said, but they found no reason to suspect foul play. Local news media said Mr. Lam had recently come down with a cold and that his wife had found him unresponsive in his bed.

After the unexpected success of his fourth feature film, the action-comedy “Aces Go Places IV” (1986), Mr. Lam was offered a rare opportunity: to write and shoot any film he wanted to make so long as the budget was under 4 million Hong Kong dollars, the equivalent of about $1.1 million today.

“I was puzzled, and at first I didn’t know what to film,” Mr. Lam said in a 2015 interview. “Eventually I decided that I enjoyed the realistic aspects of ‘The French Connection’ ” — the 1971 American movie directed by William Friedkin — “and that I wanted to create a film containing similar grit.”