GOLETA, Calif. >> An estimated 21,000 gallons of crude oil dumped into the ocean from a broken pipeline just off the central California coast before it was shut off on Tuesday, creating a spill stretching about 4 miles along the beach, the U.S. Coast Guard said.

Santa Barbara County health officials have shut down Refugio State Beach, the central site of the spill, though many had abandoned the site already because of the foul smell.

That smell brought county firefighters to the beach earlier in the day to discover the spill.

“They found about a half-mile slick of dark, black crude oil in the ocean,” fire Capt. Dave Zaniboni said.

They traced the oil to the onshore pipeline that spilled into a culvert that ran under the U.S. 101 freeway and through a storm drain into the ocean.

A few hours later the pipeline had been shut off, but the spill had stretched to about 4 miles of beach for about 50 yards out into the water, said Coast Guard Petty Officer Andrea Anderson.

The scenic stretch of coastline about 20 miles northwest of the pricey real estate of Santa Barbara is dotted with state-run beaches that are popular with campers, and the spill comes just a few days before the Memorial Day weekend and subsequent summer camping season begin.

The pipe is operated by Plains All American Pipeline LP, the Coast Guard said. The company did not immediately respond to phone messages seeking comment.

The stretch of coastline is also home to many oil rigs and drilling operations, and small amounts of tar and seepage show up on beaches, but in much smaller amounts.

The Coast Guard, county emergency officials and state parks officials had begun cleaning up the spill.

Boats from the nonprofit collective Clean Seas were being used in the cleanup.

There was no immediate estimate of how long the cleanup might take.

The Santa Barbara-based Environmental Defense Center said such a spill was inevitable with coastal oil development, but still unwelcome.

“To see this level of spill into such a sensitive and treasured environment is devastating to watch,” the EDC said in a statement. The group expressed special worry for the many species of whale that migrate through the area.

Sierra Club California Director Kathryn Phillips said, “Every time we hear about an oil spill, we hold our breath and hope it won’t get worse.”

She said in her statement that the spill was especially troubling because no one caught it “until several barrels of oil had already tumbled into the ocean.”

The spill came on the same stretch of coast as a 1969 oil spill that was the largest ever in U.S. waters at the time and is credited for giving rise to the modern American environmental movement. Several hundred thousand gallons from a blowout on an oil platform were spilled, and thousands of sea birds were killed along with many marine mammals.

It was later surpassed in size by 1989’s Exxon Valdez spill off Alaska and the 2010 Gulf oil spill off Louisiana.