CNN  — 

A leak in an oil pipeline caused a major spill off the coast of Southern California, sending oil spewing into the local environment and potentially harming wildlife and nearby human residents.

The volume of the spill pales in comparison to some of the US’ largest such incidents, such as the 1989 Exxon Valdez oil spill and the 2010 Deepwater Horizon spill, although the full extent of the spill won’t be known for several weeks, one local official said.

On Monday, Gov. Gavin Newsom proclaimed a state of emergency. “The state is moving to cut red tape and mobilize all available resources to protect public health and the environment,” he said in a statement.

Here is what we know so far about the spill and its resulting impact on the local environment and nearby residents.

Where is the spill?

The breach occurred about 5 miles off the coast of Huntington Beach in Orange County, local officials said.

The oil spill is the equivalent of an estimated 3,000 barrels – or 126,000 gallons – of post-production crude, though the city of Huntington Beach said the spill could be as much as 144,000 gallons.

The size of the spill was reported to be about 13 square miles, the Coast Guard said Sunday.

By midday Monday, about 4,158 gallons of oil had been removed from the water and 8,700 feet of oil boom – a term for floating barriers designed to contain an oil spill – were deployed, the US Coast Guard said.

When did the leak start?

It’s not clear when the leak began but authorities were notified late Friday of reports of an oil sheen, more than 12 hours before Amplify Energy, the owner of the line, reported it to state and federal officials, according to documents reviewed by CNN.

In an interview with CNN on Monday, Amplify CEO Martyn Willsher said a sheen was detected by company personnel Saturday morning, not Friday night.

Willsher said while there is equipment to detect the leak without visibly seeing oil spills, there were no notices of a potential leak in the line before Saturday.

Since then, the Coast Guard and Huntington Beach Police Department dispatched aircraft to access the situation, the Coast Guard said.

What was the cause?

A bird balances on a boom, a temporary floating barrier to contain oil which seeped into Talbert Marsh, home to around 90 bird species, after the offshore oil spill.

An anchor hooking an oil pipeline may have caused the spill, the federal Pipeline and Hazardous Materials Safety Administration said in a notice to Amplify Energy. But no cause has been officially confirmed.

“The pipeline has essentially been pulled like a bow string. And so at its widest point is about 105 feet away from where it was. So it is kind of an almost a semicircle,” Willsher said at a press conference Tuesday.

There is no confirmation of a vessel above the site of the spill, but a response team is working with other agencies to determine whether a ship was in the area, said Capt. Rebecca Ore, the commanding officer at US Coast Guard Sector Los Angeles-Long Beach.

Authorities said a 4,000-foot section of the pipeline was displaced laterally about 105 feet and had a 13-inch split that was likely the source of the spill.

“These ships are anchored and many are awaiting entry into the San Pedro Bay Port complex – the ports of Los Angeles and Long Beach – and in the course of transit it is possible that they would transit over pipeline,” Ore said Monday.

Amplify’s pipeline was due for another inspection at the end of this month, Gov. Newsom said Tuesday. While there were no issues with the pipeline during previous inspections, officials are going back to the details of those reports.

What’s the impact so far?

A dead fish is seen after an oil spill in Huntington Beach, California, on Monday, October 4.

The oil spill has coated nearby areas with oil, shut down beaches, threatened wildlife habitats and potentially harmed people.

Local governments took steps to keep people away from oiled areas.

Sections of the shoreline at Huntington Beach were closed this weekend, Orange County health officials advised residents to avoid recreational activities on the coastline, the city of Laguna Beach closed its beaches Sunday night and Newport Beach advised people to avoid contact with ocean water and beach areas impacted by oil.

The extent of the ecological damage remains to be seen.

Orange County Supervisor Katrina Foley said Sunday dead birds and fish were washing up on the shore.