Some witnesses said he said nothing. There are some that say he made a barking noise.
How easy, in the USA, for an absolute lunatic to get a gun and kill Brown U. students and an MIT professor.
The motive is also easy: Loser Kills Winner. Graduated from the same school in Portugal as a man who went on to lead a lab at MIT, while this guy went nowhere. Ditto for the Brown students – he dropped out of Brown; they were succeeding there. All had to die.