The multi-day operation was expected to target hundreds of recently-arrived families in about 10 cities who have been ordered deported by an immigration judge.

The removal operations are meant to deter a surge in Central American families fleeing poverty and gang violence in their home countries, with many seeking asylum in the United States.

Immigrants and their advocates were on standby for mass arrests, but by Sunday night there were only reports of low-profile operations in a few cities.

"Immigrants and immigrant communities all over the country are in hiding and people are living in these terrified, terrorised ways, because that is the point of this whole action, whether enforcement actions take place or not," said Mary Bauer at the Southern Poverty Law Centre (SPLC).

The Miami-based Florida Immigrant Coalition said immigrants were sheltering at home after ICE agents were seen near the city's international airport. No arrests were reported.

"They've been stocking up on groceries and making plans to stay in their homes with the lights off and the blinds down," the group posted on Facebook. "Some are staying home from work."

An ICE spokeswoman declined to comment on operations, citing the safety of the agency's personnel.

The operations came as the Trump administration faces criticism for housing immigrants in overcrowded, unsanitary conditions and there are concerns about migrant children being separated from adults by US authorities.

"While we haven't heard of widespread sweeps, none of our communities should have to live in fear that parents won't come home from work, or kids won't return from school," said Lauren Weiner, communications director for the American Civil Liberties Union, which sued this week to stop the arrests going ahead.

Amid protests outside ICE facilities, a 69-year-old gunman was shot dead by police early on Saturday after he attacked an immigration detention centre in Tacoma, Washington and set fire to at least one vehicle outside.

Australian Associated Press