Pro-Palestinian protesters occupy Columbia University building

Pro-Palestinian activists occupied a building at Columbia University early on Tuesday, escalating a battle with administrators who have begun suspending students for refusing to dismantle tents set up on the New York campus.

Protesters entered Hamilton Hall - the site of student protests dating back to the 1960s - and suspended a banner reading "Hind's Hall" from an upper floor. Others outside blocked the doors with outdoor tables and linked arms to form a barricade in front.

"This building is liberated in honor of Hind, a six-year-old Palestinian child murdered in Gaza by the Israeli occupation forces funded by Columbia University," a protester shouted from inside, with those outside repeating each phrase.

Israel has denied targeting civilians in its war on Hamas in Gaza, accusing the militants of hiding among them.

Minutes after the protesters gained access to the building, New York City police officers arrived outside the school gates in unmarked cars, the Columbia Spectator newspaper reported. It said police told the paper they would only enter school grounds if someone was injured.

Some three hours after students entered the Columbia building, the school sent out a notice saying that effective immediately access to the campus has been limited to students residing in residential buildings on campus and employees providing essential services.

"This access restriction will remain in place until circumstances allow otherwise," it said. "The safety of every single member of this community is paramount. We thank you for your patience, cooperation and understanding."

The building occupation at Columbia is at the center of Gaza-related protests roiling university campuses across the U.S. in recent weeks.

Students at dozens of campuses from California to New England have set up similar tent encampments to demonstrate their anger over the Israeli operation in Gaza and the perceived complicity of their schools in it.

The pro-Palestinian rallies have sparked intense campus debate over where school officials should draw the line between freedom of expression and hate speech.

On Monday, Columbia University began suspending pro-Palestinian student activists who refused to dismantle the protest camp on the campus after the Ivy League school declared a stalemate in talks seeking to end the demonstration.

University President Nemat Minouche Shafik said in a statement that days of negotiations between student organizers and academic leaders had failed to persuade demonstrators to remove the dozens of tents set up to express opposition to Israel's war in Gaza.

Protesters on the Manhattan campus are demanding that Columbia meets three demands: divestment in Israel, transparency in university finances, and amnesty for students and faculty disciplined for their part in the protests.

Shafik this week said Columbia would not divest from finances in Israel. Instead, she offered to invest in health and education in Gaza and make Columbia's direct investment holdings more transparent.

PROTESTS ACROSS THE UNITED STATES

At Cal Poly Humboldt University, police early on Tuesday swarmed the campus, where students were occupying a school building, and starting detaining people, local media reported.

Police late on Monday had declared the protest an unlawful assembly and warned people they faced arrest if they did not disperse.

The campus was earlier closed to all people except students and faculty because of the ongoing protest. Neither the school nor a police spokesman was immediately available for comment or to detail how many people may have been detained.

Civil rights groups have criticized law enforcement tactics on some campuses where police have clashed with protesters and have used chemical irritants to disperse crowds.

Police detained about 30 protesters at their encampment at the University of North Carolina in Chapel Hill early on Tuesday after the university gave them until 6 a.m. local time to disperse, according to a statement from the school, noting that students had trespassed into classroom buildings overnight.

"After the area was cleared, the remaining protesters escalated their tactics, attempting to forcibly enter South Building by pushing officers," the school said.

At the University of Texas at Austin, police arrested dozens of students whom they doused with pepper spray at a pro-Palestinian rally on Monday.

At least 100 were arrested during the demonstration as protesters chanted "Free Palestine" and erected dozens of tents in an encampment, local media reported.

The new encampment was an escalation by protesters after almost 60 people were arrested and charged with criminal trespassing during a protest on campus last week.

At Virginia Commonwealth University in Richmond, protesters squared off with police who used chemical irritants on the crowd and detained numerous people. The protesters had set up a "liberation zone" of tents surrounded by barriers.

“After repeated warnings and refusal to disperse, law enforcement must protect Virginians," Virginia Governor Glenn Youngkin, a Republican, wrote on social media after the incident.