Northbound F trains are stopping along the A line from Jay St-MetroTech to 42 St-Port Authority Bus Terminal, then over the E line to 36 St(Qns). FDNY is en-route to 2 Av responding. Stay tuned for updates. — NYCT Subway (@NYCTSubway) January 21, 2018

F service has resumed. https://t.co/KjcfGWHu8I — NYCT Subway (@NYCTSubway) January 21, 2018

NEW YORK (WABC) -- Video shows an unknown item, possibly a bag or jacket, burst into flames on a New York City subway seat in an incident that triggered service changes over the weekend.The fire started on a northbound F train at the Second Avenue subway station in Manhattan early Saturday morning.The incident rerouted F trains first to the A line, then over to the E line.Service resumed within an hour.Authorities have not confirmed how the fire started or who caused it.