Protesters remained posted up outside Portland's Immigration and Customs Enforcement headquarters Tuesday morning, more than 24 hours after officials first threatened arrest if they stayed on federal property.

A federal official said no specific timeline has been established for detaining protesters who continue the round-the-clock occupation. And an organizer of the demonstration — waged in opposition to the Trump administration's immigration crackdown — said protesters have no plans to leave.

A showdown could ignite at any time, however, as federal law enforcement agents remain inside the shuttered ICE building, which closed last week in response to the growing demonstration.

"People are going to do whatever it takes," said Jacob Bureros, an organizer of the Occupy ICE PDX movement. "If they arrest us on federal property, we'll shut the roads down. You can't stop us. They're going to find out that this city has more resolve they do."

The occupation, in place for over a week, consists of a sea of tents set up outside the federal building, which includes a temporary holding facility for immigrant detainees. Federal officers entered the Southwest Macadam Avenue building overnight Monday, presumably sneaking past sleeping demonstrators, and officers later notified demonstrators they must start to vacate federal property.

"It is unlawful under federal law to obstruct the entrances, foyers, lobbies, corridors, offices and/or parking lots of federal facilities," reads a flier Federal Protective Service agents distributed to protesters.

Those who obstruct the entrance to the building, according to the flier, face arrest and prosecution in federal court. However, officials acknowledged they had no authority over adjacent properties the camp has spilled onto.

Bureros said he believes the de-facto eviction notices were a scare tactic to discourage protesters.

"I'm assuming giving out notices was meant to intimidate people," said Bureros, an organizer with Direct Action Alliance, a group that helped organize the occupation. "Federal charges sound scary and all of that. But they must live in a different world than we do. I don't know how it's supposed to discourage us when they're kidnapping children and holding families in prison."

The protest has mounted in response to the Trump administration's immigration crackdown, including its policy of separating migrant children from their parents at the U.S. border.

Protesters around the country, including those in Portland, have also called for the abolishment of ICE. Such a proposal has garnered support among some Oregon elected officials, including U.S. Rep. Earl Blumenauer, a Portland Democrat.

Demonstrations have also spread to other ICE facilities around the country.

A flier was again distributed to Portland occupiers Tuesday, according to Robert Sperling, a Federal Protective Service spokesman.

He said an undisclosed number of federal agents remained inside the ICE building to maintain its security and that one of them on Monday fired a pair of "pepper balls" into the ground as a warning to demonstrators who were trying to lock federal agents inside. The demonstrators had used tape and rebar to barricade one of the building's doors, he said, and "were effectively trying to trap individuals inside."

The pepper balls were fired after the protesters had been given verbal warnings, Sperling said.

Bureros, the occupation organizer, called the agency's allegations "complete nonsense," and said occupiers haven't tried to barricade the doors.

They did put tape on door handles but didn't use any rebar or other materials, he said, noting that demonstrators have constructed barricades on the sidewalk of the property in order to protect people from being struck by anything potentially thrown from the street.

Video footage of the confrontation doesn't appear to show anyone trying to put rebar on the door, though it does appear tape had been put on door handles. The footage doesn't show the entire scene.

Around 7 p.m. Tuesday, a group of 10 protesters linked their arms together with what appeared to be PVC pipes and cord.

Though this display did not last more than a few minutes, Marquez Luis, an organizer with Direct Action Alliance, said it was meant as a "symbolic gesture" to show occupiers do not plan to leave until the facility is shut down.

When asked whether or not occupiers plan to stay put if ICE begins to force them out, Luis replied, "whether one or thousands, people will be here."

His message for ICE agents? "You don't have to be an agent of genocide. Quit and come join us."

— Jim Ryan, Shane Dixon Kavanaugh and Anna Spoerre