Members of the Church of Jesus Christ of Latter-day Saints have donated thousands of dollars to the family of the man believed to have carried out a deadly attack on one of their churches in Michigan, killing four people.

Police said Thomas Sanford drove his truck into the church in Grand Blanc during a worship service on Sunday and opened fire before starting a massive blaze. He was killed by police.

David Butler, a member of the denomination living in Utah, said he was moved to launch a fundraiser for Sanford's widow and children.

As of Thursday, it had brought in more than $250,000 (£186,000), with many donors identifying themselves as Latter-day Saints, commonly called Mormons.

"The family will face financial hardship and psychological trauma as a result of this week's horrifying events," Mr Butler wrote in the fundraiser page on the website GiveSendGo.

"On top of that, one of the Sanford sons deals with serious medical challenges that require ongoing care, treatment, and specialized support."

• What we know about Michigan church shooting and arson attack

Mr Butler said he had no connection to the Sanford family or to Grand Blanc, describing himself as "an ordinary member" of the Church of Jesus Christ of Latter-day Saints. He is also a fantasy and science fiction writer.

But he added that he felt compelled to start the fundraiser "to create some stability in a time of heartbreak and upheaval" for Sanford's family.

Donations, he said, will go towards their daily needs and medical treatment.

Some donors listed on the page are anonymous, but many left comments describing themselves as Latter-day Saints.

"God loves you and your family and I wish I could give you a big hug," wrote one donor.

"The members of The Church of Jesus Christ of Latter-day Saints love ALL of you and hope you are able to heal with them," wrote another.

The New York Times reported that some people on-line have criticised the fundraiser.

Eight people were also injured in the attack, which police believe was a "targeted act of violence".

It shocked the local community and church nationwide.

Money has also been donated to fundraisers for victims and their families. Flags were lowered throughout Michigan to honour the victims, and neighbours, including members of other denominations, have held vigils.

One survivor of the attack wrote in a letter that she had forgiven the gunman for killing her father.

"When he [the gunman] came over to me I felt very calm, peaceful even as I kneeled next to my dad, my hands still on dad," the woman wrote in the letter, shared with BBC's US partner CBS News. Her name was not published to protect the family's privacy.

"I never took my eyes off his eyes, something happened, I saw pain, he felt lost. I deeply felt it with every fiber of my being," she wrote.

"I forgave him, I forgave him right there, not in words, but with my heart."

Investigators said earlier this week that they are still searching for a motive behind the attack, which happened during a Sunday service attended by hundreds of people.

Officials have said Sanford, 40, was a former Marine who was once deployed to Iraq. In an old interview with local outlet Clarkston News, Sanford said that he was a sergeant and served in Fallujah in 2007.

He had previous arrests for burglary and operating a vehicle while intoxicated, officials said on Monday. Sanford is from a suburb of Flint of about 30,000 people, just a few miles away from Grand Blanc Township.