Salt Lake City, Utah — Hours after hundreds of people welcoming missionaries from the Church of Jesus Christ of Latter-day Saints crowded together in an airport parking garage, authorities Monday announced new rules to prevent it from happening again during the coronavirus crisis.

The people who showed up Sunday at the Salt Lake City Airport and stood shoulder-to-shoulder, some hugging arriving loved ones, should have heeded warnings to keep their distance to help prevent the spread of the virus, said critics of the gathering including U.S. Sen. Mitt Romney, Utah's governor and lieutenant governor and the church itself.

While Utah residents welcoming returning missionaries are an airport tradition, officials this time asked for only one or two family members of each returning missionary to come and to stay in their cars - guidance that wasn't followed by many people, said airport spokeswoman Nancy Volmer.

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Church officials said in a letter that they appreciate the love and care from families and acknowledge these are "unprecedented times" but made clear what happened can't occur again.

"What occurred Sunday afternoon at the Salt Lake airport causes us deep concern with missionaries and their families disregarding important instructions regarding self-isolation and congregating at airports," the letter said.

Mormons crowd Salt Lake City Airport greeting returning missionaries despite coronavirus social gathering guidelines onf March 22, 2020. KUTV

Under new rules announced Monday afternoon by Salt Lake City officials, only one car per returning missionary will be allowed at a designated spots in the garage. Airport staff will direct the missionaries to the designated spot while airport security will ensure compliance. The city rules were agreed to by the city, church and the airport.

Video and photos showed many people inside the parking garage standing much closer to each other than the recommended "social distancing" measure of 6 feet apart.

"This is irresponsible," Romney wrote on Facebook. "Parents, please pick up your missionary from the airport alone and help them strictly follow self-quarantine procedures for their first 14 days at home. We need to work together to keep our communities safe."

The first-term Republican senator has put himself in quarantine because he sat next to Kentucky Sen. Rand Paul, who tested positive for COVID-19.

The 900 missionaries who arrived at the airport were returning from the Philippines on chartered flights. Thousands more missionaries are expected to return from abroad in the coming days and weeks after the Utah-based faith said Friday it was bringing home an unspecified but "substantial" number of missionaries.

Utah Gov. Gary Herbert called the airport event "dangerous" in a tweet and Lt. Gov. Spencer Cox said he was "really disappointed in the behavior we saw from missionary families at the SLC airport tonight."

"I get it, I've been there (and still have a child serving), but this is unacceptable. In a time of shared sacrifice, we must do better to save lives," said Cox, a member of the faith widely known as the Mormon church, as are Romney and Hebert.

Rep. John Curtis tweeted a video of the gathering with the caption, "Watch the below video for what NOT to do."

The church posted a statement online Sunday night urging parents to go alone to pick up their family members and to maintain recommended distance apart from them and for the missionaries to go into 14 days of self-isolation.

Regional church leaders were told Saturday to tell parents to take only one vehicle to the airport and stay in their cars, church spokesman Daniel Woodruff said.

CBS Salt Lake City affiliate KUTV reports some families of the returnees didn't take part in the airport scene and found other ways to welcome loved ones home.

For instance, Ashely Shell's neighborhood cheered her brother Cayden, who'd been in Singapore.

"They all lined up on our street and created posters that said, 'welcome home, we love you.' Some people even had confetti, and flags, and fireworks. It was quite the scene," Shell said.

There are no confirmed cases of coronavirus among the missionaries, said Woodruff, declining to comment on the criticism from Romney and the other political leaders.

It is a tradition for large groups of family and friends to squeeze into the arrivals greeting area at Salt Lake City airport's to welcome home missionaries with signs, screams of joy and balloons. The official reaction to Sunday's event illustrated how religions are being forced to alter customs amid the spread of the coronavirus.

The church's proselytizing missions are an integral part of the religion and considered rites of passages for young members. Men serve two years while women serve 18 months. There were about 65,000 people serving missions before the coronavirus pandemic started.

The church has said it doesn't plan to suspend its missionary program. The faith is sending home many missionaries serving or preparing to serve in foreign countries so they can self-isolate for 14 days and be reassigned to continue on missions in their home countries.