Thousands of strangers have rallied to support the grieving husband of an El Paso shooting victim, who has issued an open invitation to his late wife's funeral on Friday.

A social media post by the funeral home arranging the service said Antonio Basco, 61, was married for 22 years to his wife Margie Reckard and he had no other family.

"He welcomes anyone to attend his wife's services," it said.

The post has been shared more than 13,000 times with almost 2,000 comments from people offering their condolences.

"Just sent flowers from Los Angeles, CA. I pray Mr Basco knows he and his beloved Margie are in the thoughts of many, including this stranger," wrote one Facebook user.

"Prayers. May God give him strength at this difficult time. Planning on being there. #ElPasoStrong," added another.

Antonio Basco hasn't left Walmart since his wife, Margie Reckard, died. He'd been living out of his car, which had broken A/C, and sleeping on the ground next to her cross to clean off the dead flowers in the am. El Paso rallied: fixed his car, got him a hotel, brought him food pic.twitter.com/CmM7mATYuy — Brianna Sacks (@bri_sacks) August 14, 2019

Awww man...this hurts 💔. My prayers go out to Antonio Basco. I hope El Paso packs out that funeral and he is showered with love from those who want to be his family. #ElPasoStrong https://t.co/EWuG72ESvi — Andre Littlejohn (@andrelittlejohn) August 14, 2019

On Thursday morning, the organiser said it would be relocating the service to a larger venue in El Paso, Texas, "due to the overwhelming response of the community".

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Mrs Reckard, 63, was one of 22 victims who died after a white supremacist opened fire inside the Walmart near the Cielo Vista Mall on 3 August.

In the days after the massacre, her husband was photographed mourning her death at a makeshift memorial and hugging a white cross with her name on it.

AAP

Funeral home director Harrison B Johnson told the BBC the company would be covering the full cost of the funeral with no cost to Mr Basco.

"We have had a tremendous outpouring of support after we shared the post. It is our privilege to honour and serve the community to try and make that burden lighter after a tragedy that has devastated our community," he said.

"We just wanted to do our part to help in some small way."

A prayer service for Mrs Reckard will be held in El Paso on Friday evening, before her funeral on Saturday morning.