With ICE agents going door-to-door in Colorado, residents are on edge: Reporter's notebook

DENVER -- A text from a source illuminated my bedside table at 5:45 a.m. on Wednesday.

"Get ready," it said.

Soon after, our team watched as dozens of agents from six different federal law enforcement agencies went door-to-door at a multi-building apartment complex in southeast Denver, displaying a significant change in the aggressiveness of our country's immigration enforcement.

Since President Donald Trump took office again on Jan. 20, federal law enforcement, especially U.S. Immigration and Customs Enforcement (ICE) and the Drug Enforcement Administration (DEA), have been tasked to increase their number of arrests to show that the new administration is making good on its promise to deport undocumented immigrants.

When ABC News correspondent Mola Lenghi and I started chasing these operations last week in Colorado – learning about them ahead of time through a variety of sources, including tips from law enforcement directly involved in the actions – they were heavily focused on suspected undocumented immigrants accused of illegal drug and gun trafficking.

We watched one DEA-led pre-dawn raid at a house in the Denver suburb of Brighton yield at least three people we were told were suspected Sinaloa Cartel members under investigation for fentanyl and gun trafficking. Just an hour after that raid began, agents walked out of the house with multiple bags and assault-style rifles as alleged evidence.

Other operations at apartment complexes in Aurora and Denver appeared highly targeted against specific residences. Government spokespersons had a consistent message for the press during this surge of enforcement: They were targeting the most dangerous undocumented individuals.

But when our team arrived on scene at an apartment complex in southeast Denver Wednesday morning after the early-morning tip, we saw a different scene than what we are being told in public statements from ICE, DEA and similar law enforcement agencies. We watched as dozens of federal agents went door-to-door, questioning residents at every apartment in the massive complex, asking for identification and if they had drugs or guns inside their unit.

One woman gave me her video doorbell camera footage showing two agents, one of them wearing a vest that displayed Homeland Security Investigations (HSI) markings, knock on her door and ask if she had guns or drugs inside the house and if they could "come in and check." The woman answered no to each question before the agent said thank you and left for the next apartment.

The resident told us the agents did not present a warrant or explain why they were there.  Several residents with whom we spoke told us that the agents did not skip a single residence in the complex.

A law enforcement source directly involved in the operation told ABC News that at least two warrants were served on units in the complex in connection with a drug trafficking investigation. The apartment complex had long been described in local news reports as a hot spot for illegal activity.

What we witnessed, however, did not appear specific or targeted. This operation reflected a clear and dramatic shift in the posture of federal law enforcement toward people who, in the eyes of investigators, may be undocumented.

We watched agents approach one young man in his car as he was leaving the parking lot. They questioned him for several minutes before ordering him out of the vehicle and detaining him in the back of an unmarked vehicle.

Thousands gathered outside the Colorado State Capitol building on Wednesday afternoon to protest the door-to-door operation. Two teachers employed by Denver Public Schools told me they are having meetings and receiving documents to provide guidance about how to address the constant questions from students who are afraid and don't know if they're safe.

There also is now a robust operation of activists and attorneys who arrive at these raids soon after the first reporters do to advise people of their rights regarding the sweeps, using megaphones to shout the information in both English and Spanish.

One undocumented young man told me earlier this week that he's stopped going to work at a local moving company because of the threat of ICE arriving at his workplace and detaining him.

A few hours after reporting on Wednesday morning's operation, our ABC News team was denied access to a press briefing from Tim Lenzen, acting special agent in charge of Denver's HSI office. Only three local television news stations were allowed in. No reason was given for ABC News being barred from the briefing.

The previous days of immigration enforcement in Colorado specifically targeting only the most dangerous individuals seems to be fading. A life of fear at home, at work and at school for undocumented families is coming increasingly into focus, according to teachers and residents we have interviewed this week.

As Trump's newly-appointed "border czar," Tom Homan, told ABC News "This Week" co-anchor Martha Raddatz: "If you're in the country illegally, you're on the table."