Investigators work scene of Kobe Bryant's chopper crash

Investigators worked Monday on a rugged hillside outside Los Angeles where a helicopter carrying Kobe Bryant and eight others crashed in foggy weather considered dangerous enough that local police departments had grounded their choppers.

About 20 investigators were on the scene where everyone aboard was killed Sunday morning in a wreck that left debris scattered over an area the size of a football field. The accident generated an outpouring of grief and shock around the world over the sudden loss of the all-time basketball great who spent his entire 20-year career with the Los Angeles Lakers.

Thousands of fans, many wearing Bryant jerseys and chanting his name, gathered outside the Staples Center in downtown Los Angeles, home of the Lakers and site of Sunday's Grammy Awards, where Bryant was honoured.

The 41-year-old Bryant, who perished with his 13-year-old daughter, Gianna, was one of the game’s most popular players, an 18-time All-Star who helped lead the Lakers to five NBA championships.

The cause of the crash was unknown, but conditions at the time were such that the Los Angeles Police Department and the county sheriff's department grounded their helicopters.

The Los Angeles County medical examiner, Dr. Jonathan Lucas, said the rugged terrain complicated efforts to recover the remains. He estimated it would take at least a couple of days to complete the task.

The Sikorsky S-76 went down in Calabasas, about 30 miles northwest of downtown Los Angeles. Authorities did not say where Bryant was going, but the helicopter appeared headed in the direction of his youth sports academy in nearby Thousand Oaks, which was holding a basketball tournament Sunday in which Bryant's daughter, known as GiGi, was competing.

Bryant’s helicopter left Santa Ana in Orange County, south of Los Angeles, shortly after 9 a.m., heading north and then west. Air traffic controllers noted poor visibility around Burbank to the north and Van Nuys to the northwest. The aircraft crashed into the hillside around 9:45 a.m. at about 1,400 feet, according to data from Flightradar24.

When it struck the ground, the helicopter was flying at about 160 knots (184 mph) and descending at a rate of more than 4,000 feet per minute, the data showed.

Federal safety investigators will look at the pilot's history and the chopper's maintenance records, said National Transportation Safety Board board member Jennifer Homendy.

Kurt Deetz, a pilot who used to fly Bryant in the chopper, said the crash was more likely caused by bad weather than by engine or other mechanical problems.

“The likelihood of a catastrophic twin engine failure on that aircraft — it just doesn’t happen,” he told the Los Angeles Times.

Justin Green, an aviation attorney in New York who flew helicopters in the Marine Corps, said pilots can become disoriented in low visibility, losing track of which direction is up. Green said a pilot flying an S-76 would be instrument-rated, meaning that person could fly the helicopter without relying on visual cues from outside.

Colin Storm was in his living room in Calabasas when he heard what sounded to him like a low-flying airplane or helicopter.

"It was very foggy so we couldn’t see anything,” he said. “But then we heard some sputtering and then a boom.”

The fog cleared a bit, and Storm could see smoke rising from the hillside in front of his home.

Firefighters hiked in with medical equipment and hoses, and medical personnel rappelled to the site from a helicopter but found no survivors, authorities said.