Five people were killed Sunday when a small plane trying to make an emergency landing crashed in a busy shopping center parking lot in Southern California, authorities said.

The twin-engine Cessna went down at about 12:30 p.m. PT (3:30 p.m. ET) in Orange County, southeast of Los Angeles. It was trying to land at John Wayne Airport in Santa Ana, about 1½ miles away.

No one on the ground was injured, but an unoccupied car in the parking lot outside a Staples store was extensively damaged.

The plane had left Concord, northeast of San Francisco, according to Orange County Fire Capt. Tony Bommarito. A fire crew was eating lunch just down the street, "so they were on the scene within a minute," he said.

The Orange County Coroner's office identified the victims early Monday as Scott Shepherd, 53, and wife Lara, 42, of Diablo; Floria Hakimi, 62, of Danville; Navid Hakimi, 32, of Los Angeles; and Nasim Ghanadan, 29, of Alamo.

It was not immediately clear who was piloting the aircraft.

An investigator looks over the wreckage of a small plane that crashed near Santa Ana, California, on Sunday. Eugene Garcia / EPA

"We are shocked and heartbroken by the tragic loss of life from the plane crash in Santa Ana, California Sunday," the Shepherd family said in a statement. "Scott and Lara will be deeply missed. They were wonderful parents."

The family of Nasim Ghanadan told NBC Bay Area that she worked for a real estate company called Pacific Union International in Danville, California.

An aunt in a statement said Ghanadan was "the life and joy of our family" and said the family is trying to make sense of her death.

"Why would this have to happen to us? Nasim was at the prime of her life," the statement said. "How can this be? Why would anyone put this many people on an unreliable plane? Why?"

Pacific Union's CEO said in a statement that all five people on board, including the pilot, either worked under the company or were related to one of them.

"We are shocked and deeply saddened by the news of this tragedy," CEO Mark McLaughlin said. "Our entire Pacific Union family is mourning the loss of our colleagues, family and friends."

Peter Knudson, a spokesman for the National Transportation Safety Board, which is investigating along with the Federal Aviation Administration, said the plane had been given approval to land at John Wayne after the pilot declared an emergency.

Information on the nature of the emergency wasn't made available Monday.

Knudson said the pilot didn't declare a flight plan and had decided to fly under visual flight rules, which isn't uncommon in good, clear weather.

Bommarito, the fire official, said it appeared that the plane "went down pretty abruptly." He added that while the plane leaked jet fuel, it didn't ignite.

"I don't know anything about what this pilot did or what he was thinking, but it could have been much more tragic," Bommarito said. "This was a Sunday afternoon, and we have people shopping, so the fact that we have no injuries on the ground is a miracle in itself."

Other small plane crashes elsewhere in the country over the weekend resulted in multiple deaths or missing passengers.

In northern Oklahoma, five people, including two children, were killed Saturday morning when the single-engine plane they were riding in crashed in a soybean field, reported NBC affiliate KFOR.

Two men were also killed Saturday morning near Mobile, Alabama, after their plane crashed in a sod field as they were attempting to hook an advertising banner to the aircraft, according to NBC affiliate WPMI.

Meanwhile, rescue crews were trying to reach a pilot and four passengers who were on a tour plane that crashed Saturday night in the Alaska Range in Denali National Park. Bad weather forced the search to be called off Sunday, but it was expected to resume Monday, officials said.

The pilot was able to make two calls on a satellite phone to alert the tour company's airport office about the accident. "The pilot reported injuries, but the extent is unknown," the National Park Service said in a statement Sunday.