The authorities identified the attacker as a 20-year-old student at the university, and said he appeared to have been acting alone.

Students on Thursday protested the president’s attacks on Harvard, but at town hall meetings, defiance mixed with uncertainty as faculty members examined the toll of the White House’s actions.

The Trump administration said it would take $2.2 billion in research funds from the school. Some small donors are doing their best to make up for the shortfall.