A 71-year-old Arizona man was shot to death while driving for Lyft, just minutes after he spoke to his wife on the phone to wish her a happy 52nd wedding anniversary.

Harold Treadwell was fatally shot in the early hours of Sunday while in his car, Phoenix police and his wife, Frances Treadwell, told NBC News.

Authorities said in a statement that Treadwell was the only person in the car at the time and they believe the bullet was fired from outside the vehicle.

Frances Treadwell said the shooting occurred on their wedding anniversary. "I feel like I am living a horrible nightmare," she said. "I wish I could wake up and he would still be sitting here."

Frances and Harold Treadwell had been married for 52 years and been together since she graduated high school. "He was my best friend," she said. Together, the couple had two children, three grandchildren and two great-grandchildren.

Treadwell was a retired financial planner who drove Lyft part-time to bring in extra income. Frances Treadwell said he left the house Saturday between 5-6 p.m. to drive Lyft, stopped back at home around 8 p.m. for dinner, and went out again to drive more.

Phone records show the couple spoke at 12:28 a.m. Sunday, and police say Treadwell was murdered just after 12:30 a.m. Frances Treadwell said her husband told her on the phone he was headed home but she said it wasn't unusual for him to work through the night.

At 4:30 a.m. Sunday, police knocked on the door of the Treadwells' Phoenix home, telling Frances Treadwell her husband was involved in a homicide.

She told NBC News she's grief-stricken, devastated and worried about her financial future. They didn't have life insurance for him and she says she will lose his benefits.

A friend created a GoFundMe for the family and Frances Treadwell says the money will go toward funeral expenses. "I had no money for cremation," she said, thanking the people who have already donated just shy of $5,000. "I didn't know what GoFundMe was," she added.

Police are investigating the killing and say they currently don’t have any suspects.

In a statement, Lyft said it is assisting law enforcement with the investigation.

“We are deeply saddened and shocked by this loss," the ride-share company said. "Our sympathies go out to the loved ones of Harold Treadwell and all those impacted by this tragedy.”

Frances Treadwell pleaded for anyone with information to come forward and contact the Phoenix police. "He had no enemies," she said of her husband. "I need help finding who did this. I want justice."