A fire at Grand Central Terminal Tuesday threw Long Island Rail Road service into chaos for thousands of morning commuters.

There was a massive FDNY response to the fire, which filled tunnels with smoke and sparked closures and diversions across the system before service out of Grand Central was restored at 2:41 p.m.

“A two-alarm fire broke out at Grand Central Terminal this morning,” New York City Emergency Management said on X Tuesday morning. “The fire and smoke has caused widespread disruptions across the Long Island Rail Road and related transit systems.”

LIRR officials said eight branches were affected, with suspensions or rerouted trains along the Babylon, City Terminal Zone, Hempstead, Far Rockaway, Port Jefferson, Port Washington, Ronkonkoma and West Hempstead branches.

“Some westbound trains will be canceled upon arrival in Jamaica and diverted to Penn Station or Atlantic Terminal,” the railroad said on X. “Subways are cross-honoring LIRR fares.”

More than 100 firefighters were on the scene battling the fire for hours, and eventually getting the flames under control, FDNY Fire Commissioner Robert Tucker said.

“[There is] absolutely zero visibility down there, firefighters were met with heavy, heavy smoke and a significant amount of fire when they located the room where the fire was coming from,” Tucker said. 

Three firefighters and one LIRR power department employee were injured during the fire, he revealed. 

No passengers had to be evacuated from any trains, which were rerouted to Penn Station and other stops as the FDNY requested that power be cut to certain areas and tracks, MTA officials said.

The cause of the fire was still under investigation, authorities said.