The old Ruby’s Diner building at the end of the Seal Beach Pier was gutted by a spectacular fire that sent smoke towering over the coastline Friday morning.

The fire was first reported about 7:45 a.m., Orange County Fire Authority Capt. Larry Kurtz said.

The building that burned was once home to a Ruby’s Diner, which closed in 2013. Smoke was still coming out of the gutted structure more than 7 hours after the fire broke out, and firefighter expected it would be smoking for hours to come.

Aerial video from Sky5 showed three boats initially surrounding the old restaurant, using water cannons to douse the flames.

“A fire on a building at the end of a pier is definitely a challenge,” Kurtz said.

Firefighters ran hose for hundreds of feet down the course of the pier, and boats from the Long Beach Fire Department were helping, he said. Dozens of fire engines could also be seen parked near the pier.

Crews tried to keep the flames from burning too much of the actual pier, Kurtz said.

A fourth boat, described as the largest fire boat on the West Coast in a tweet by the Long Beach Fire Department, later joined the fight and put two more large streams of water onto the flames.

The intense streams of water coming from the Long Beach boat was so strong it stripped roofing off the burning building, video showed.

The roof appeared to have collapsed once the flames were largely extinguished. It was not clear how much damaged was done to the pier itself.

Kurtz said he did not know when fire inspectors had last visited the building.

The restaurant’s closure prompted a fence to be erected to keep people from going into the abandoned structure, Seal Beach Police Department Lt. Michael Henderson said.

The fence has been a sore spot in the community, where some have called for the business to be torn down so access to the end of the pier could be restored.

Friday’s fire was not the first incident to leave the pier in need of repair.

A storm in 1983 tore more than a thousand feet of deck off the pier’s pilings, the Los Angeles Times reported.

It was damaged again when fires struck in 1992 and 1994, according to the Times.

And just last year, powerful winds and surf from Hurricane Marie caused some structural damage, the Orange County Register reported.

The cause of Friday’s fire was under investigation and firefighters continued to overhaul the scene in the afternoon hours.

Investigators from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were aiding in the case, Kurtz said.

“We’re going to be here for probably a few more hours. It’s dirty work; it’s very long work. But we are going to find out what caused this fire,” Kurtz said.

The pier will likely remain closed until the fire’s cause has been determined.

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