Fire is a combustion that creates heat and light.
In 2020, Marcus O'Herlihy intentionally caused a fire aboard the USS Lewis & Clark using a spare oxygen generator. The fire was barely put out by Alice Fontana and James T. Kirk, who was in Shaun Christopher's body. (TOS novel: The Rings of Time)
In 2249, there was a fire in Nyota Uhura's dorm room at the Institute for Advanced Mathematics. Uhura's roommate, a girl named T'iana, was trapped under a fallen beam, and Uhura was lit ablaze. Uhura was unable to save T'iana before succumbing to the effects of the heat and fire. For years afterwards, Uhura would have dreams about T'iana's death and Uhura's subsequent rescue by adults. The fear recurred most vividly in 2269 when Uhura was part of the USS Enterprise crew facing a deadly heat effect that began in the Beta Castelli star system. (TOS novel: The Three-Minute Universe)
In 2340, at the age of five, Geordi La Forge was briefly caught in a fire, and unable to escape, due to his blindness. He was rescued by his father. (TNG episode: "Hero Worship"; TNG novels: The Romulan Stratagem, Gulliver's Fugitives)