More than 100 people were arrested and four police officers were injured early Thursday when protesters clashed with Boston police as a pro-Palestinian encampment at Emerson College was cleared.The encampment is one of several set up by students at colleges nationwide to show solidarity with the pro-Palestinian protesters who were arrested at Columbia University in New York earlier this week. An Emerson student said an announcement was made at 1 a.m. that the encampment, which is off Boylston Street, saying anyone in the alley would be arrested.Boston police officers walked out of the Massachusetts Transportation Building at 2 a.m. and made their way through the crowd in the alley.Video from the scene showed dozens of officers in the area, many of whom were wearing protective gear."I saw one student get shoved to pavement and hands behind them. Protesters seemed compliant -- not fighting back or acting violent," Emerson student Kyle Graff said.Another student who was at the demonstration and left the area said he watched the incident unfold from his dorm window and said he saw officers dragging away some people who resisted arrest. "Being there and seeing the people standing around, getting dragged to the ground, getting arrested, it was horrifying. It was absolutely disgusting. I am still shaking from experience," the student said.Boston Police Department spokesman Sgt. John Boyle said 108 people were arrested and are expected to be arraigned in Boston Municipal Court.Of the four police officers injured, one suffered serious, but non-life-threatening injuries.Boylston Place Alley is not solely owned by Emerson College and it is a fire alley with a public right of way requirement to access non-Emerson buildings, including the State Transportation Center.Just outside the alley, several police vans were parked to take away protesters, and crime scene tape was placed to cordon off the area.Demonstrators have been urging college officials to support a ceasefire in Gaza and divest from companies and institutions that support Israel.The removal at Emerson comes hours after pro-Palestinian protesters set up another encampment at Harvard Yard.The ACLU said colleges are walking a tight rope balancing First Amendment rights and campus safety."We've been urging campus administrators and law enforcement to exercise restraint in interfering with student demonstrations and encampments," said Carol Rose, of the ACLU. "These are hard times for colleges and universities. Trying to balance the legal requirement that they ensure education free of discrimination at the same time to ensure the free speech rights of students."Harvard University is only allowing people with campus IDs onto Harvard Yard and there are signs indicating tents and tables are not allowed without proper permission.At MIT, police are on standby but no arrests have been made thus far in connection with the protests, nor have any threats been reported.