A fire broke out at Penn Station in New York City early Friday morning, disrupting service for thousands and injuring several people. 

Firefighters responded to a blaze on an Amtrak work train in one of the Hudson River Tunnels around 1:30 a.m., deploying 46 units and 141 personnel, officials said. The fire was brought under control just after 4 a.m., and the cause of the debacle remains under investigation.