During a summer of transit misery in New York City, a subway track fire in Upper Manhattan on Monday morning sent nine people to the hospital and snarled trains across the city.

A track fire near the 145th Street station on the A line around 7:30 a.m. halted service on several lines and prompted a cascade of delays, subway officials said. Beleaguered commuters flocked to other lines that were overcrowded and sweltering on a hot day.

Nine people were transported to hospitals to be examined, fire officials said. The fire was reportedly caused by trash on the tracks, fire officials said, and it was under control by about 9:15 a.m.