Recent tornadoes ravaged immigrant and other low-income communities in the US state of Alabama, but undocumented aliens say they are reluctant to openly seek help out of fear of arrest and deportation.

Tornadoes left a wide swath of destruction through this university city, leaving at least 39 dead and several missing, and poorer neighborhoods such as Alberta and Holt, where many immigrants and African-Americans saw their homes left in splinters, were especially hard hit.

Illegal immigrants were keeping a low profile Sunday, but about 30 of them gathered at Holy Spirit Catholic Church for a Spanish-language noon mass and to receive donations from the community.

About 20 immigrants from Mexico and Guatemala whose homes were destroyed spent the night at the church on mattresses alongside tables piled high with donated clothes, shoes and food boxes. Children ran about as women discussed the tornado terror and how unlikely it was that anyone of them had survived.

Many more have come to the makeshift shelter to receive hot meals, only to return quickly to their damaged homes, in part to reduce their exposure in front of local authorities overseeing search and rescue operations and police who have set up checkpoints to ward off looters.

While Alabama officially claims only eight missing across the state, that figure could be considerably higher, given the hesitation of some immigrants to come forward for official assistance or to report missing loved ones.

"Many people are still missing out there," said Mexican-born Susana Ortiz, who was looking for her friend Ana Rodriguez.

"What happens is that many do not want to talk, they're afraid of the police because they are illegal," said Martin Izaguirre, another volunteer who works at the shelter.

"They prefer to stay locked in their homes. They come to get food and go."

Izaguirre said Mexican consular officials were set to arrive Monday in Tuscaloosa in an effort to provide assistance to Mexican immigrant residents.

Immigration reform, and providing a path to citizenship for 12 million illegal immigrants, is one of the most bitterly divisive unresolved issues in US politics today, and immigrant populations have come under pressure in an economy still reeling from the worst recession in generations.

Jose Luis Vazquez, who lived in a low-income Tuscaloosa home with five other undocumented workers, said police in general have shown sympathy to immigrants, "but now they are trying to impose the law against immigrants like in Arizona," a US border state that has tightened rules on illegals.

"We are all OK, but the house has almost disappeared," he told AFP.

Six years ago Vazquez sneaked across the border from Mexico, where he left his wife and son to try and make it in America as an electrician.

"You have to do that to survive if you have no money. At least I have a brother here and we are both fine."

Lucio Cecilio Zacarias, who arrived at the Holy Spirit church clad in bandages and seeking a hot meal, told of how the tornado barreled through the neighborhood like a freight train, sparing nothing in its path except a few lucky souls.

"Something hit my head and I fainted. The wind threw me out of the house, and when I recovered I went up to my wife and my son who were trapped under the wood and rubble."

Local resident Sherry Malcon, 34, said she was hosting the traumatized family.

"They live very near, but my house is OK and so I'm taking care of them for now," she said.