Lack of oxygen in the water might be the cause for the death of millions of small fish, primarily sardines, at Redondo Beach's King Harbor near Los Angeles, authorities said on Wednesday.

The death of millions of fish at the harbor in the past few days has alarmed scientists, drawing various speculations about the cause.

Scientists from the California Department of Fish and Game ( CDFG) said tests showed the fish was suffocated by lack of oxygen in the water.

Driven by wind gusts reaching 45 mph, swarms of sardines, along with mackerel and perch, massed at the harbor in the past few days, leading to insufficient oxygen and lack of water movement, scientists said.

Sardines usually move in gigantic schools, sometimes called " bait balls."

CDFG spokesman Andrew Hughan said officials believe the school of fish "got lost" and made a wrong turn at the King Harbor breakwater.

Initial testing revealed no sign of natural toxins, such as domoic acid, which sometimes kills marine life, Hughan said.

Hughan said there was no health hazard, and the city was doing a good job in handling the cleanup.

The cleanup is expected to take a week and may cost about 100, 000 dollars, said Mayor Mike Gin of Redondo Beach.

The operation was complicated by dead fish near or on the bottom of the harbor decomposing and floating to the surface, officials said.

No harbor area closures were issued on Wednesday morning, but the Department of Public Works may close access for large construction equipment during the cleanup, Redondo Beach police Sgt. Dave Taneman said.

The surface of the water was covered in areas by tons of the approximately four-inch fish, in some places a foot thick, Redondo Beach police Sgt. Phil Keenan said.