A huge section of tile wall in a Brooklyn subway station came crashing down into the path of an oncoming R train early Sunday, causing one of the cars to derail and suspending service on portions of the line.

Some 30 people were stuck inside the southbound R train when the slab of tile fell onto the tracks of the 86th Street subway station in Bay Ridge around 5:30 a.m., authorities said.

While no one was injured, the incident snarled train traffic for hours, forcing the MTA to close the station for nearly 12 hours, until about 4:30 p.m.

Photographs show the large rectangle of tile lying mostly intact between the rails.

“The train is still in the station. It’s going to take a while,” said Paul Navarro, director of subway safety for the Transport Workers Union. “It’s unfortunate, but that’s what’s going to happen when you have a subway system that’s over 90 years old.”

Navarro blamed the subway station’s deterioration on “the political struggle” between Mayor de Blasio and Gov. Cuomo.

“That’s what happens when you play politics like that,” he said. “The only people that suffer are the public. They don’t take the subway.”

Zach Lounsbury, 24, who lives in Crown Heights and tutors eighth-grade students near the 86th Street stop, complained that the neighborhood is difficult to navigate when station mishaps occur.

“The R train doesn’t have much of an alternative. Everyone south of 36th Street is messed up when it’s not running,” he said. “There have been times when I haven’t been able to get to work and I just lose that work.”

One disgruntled rider told The Post that another panel fell from the wall about a year ago.

“One morning I was going to 95th Street and all the trains were running on the Manhattan-bound track,” Benjamin Roman, 45, seethed.

“One of the wall panels had fallen down into the tunnel,” he said. “You would think if that portion fell down they would check all the rest of it.”

The MTA did not immediately return a message seeking comment on the alleged past incident.

Additional reporting by Stephanie Pagones and Emily Saul