Immigration and Customs Enforcement arrested 35 people as part of an operation targeting families with deportation orders, officials said Tuesday, a number far lower than the 2,000 targeted in the highly publicized raids touted by President Donald Trump.

Of those 35 arrested, 18 were members of families with court-ordered removal orders targeted by the operation and 17 were collateral arrests of people found during enforcement actions, ICE Acting Director Matthew Albence said during a news teleconference Tuesday morning.

Albence declined to say when the arrests took place and would not name the cities where they occurred, but said they happened "nationwide in various locations."

When asked about the low arrest rate, Albence said, "this is just the beginning of the operation."

The families targeted were part of an accelerated immigration docket in 10 cities across the country, and 85 percent of those were given orders of removal in absentia, he said.

"Part of the challenge" was those immigrants could now be "anywhere in the country," Albence said.

Albence said there were other issues as well, including the high media visibility, incidents where agents believed they were being surveilled and Hurricane Barry in Louisiana, which led authorities to call off operations there.

"We are going to continue to conduct these operations," he said.

He added he “was not aware” of any circumstances from those arrests were families had to be separated for detention purposes.

In a separate operation, called Operation Cross Check, 899 people with final orders of removal were arrested between May 13 and July 11, Albence said. Of those, 605 were convicted of crimes and 93 had pending criminal charges, he said.

Officials previously told NBC News that nationwide raids targeting the roughly 2,000 migrants in 10 cities would take place starting July 14, after being postponed weeks prior.

President Donald Trump himself, who has been seeking to deter the influx of Central American families coming to the U.S. border, said the raids would take place that Sunday.

"We’re taking them out by the thousands," he said.

He has since called the enforcement operation, “very successful.”

News of the planned operation led immigrant advocacy groups to rally together to inform undocumented immigrants about what to do if they encountered immigration authorities. Those advocates also expressed concerns that the families who were ordered deported in their absence from court may have not been properly informed about their court date and could merit having their cases reopened.

Officials confirmed to NBC News that the raids had begun but that the pace had started slow.

Albence said Tuesday previous operations were conducted "without a lot of fanfare and media attention, so that certainly from an operational perspective is beneficial."

When asked if it was a problem for ICE that President Trump tweeted about the operation, Albence said "no," adding "this wasn't a secret," citing ongoing news reports about the raids.