This was the first warning issued to the demonstrators yesterday morning. A subsequent announcement asking all M. I. T. lab personnel, press, and bystanders to leave the area was repeated at nearly regular ten-minute intervals.

At 8:45 a. m. however-when City Solicitor Philip M. Cronin '53 appeared in front of the main entrance-the demonstrators appeared to have completely ignored police warnings.

Cronin and an unidentified man with him attempted to break through the picket line, struggling with demonstrators. Cronin was thrown to the ground in the scuffle, but was unhurt. The other man broke through to the door of the I-Lab, where he was greeted by seven men inside the door, shaking nightsticks and boards at the picketers.

By 9 a. m. all groups of demonstrators had come together in front of the main entrance. Police methodically unloaded their vans a few blocks away on both sides of Osborn St.

Cambridge Mayor Walter J. Sullivan was seen near I-Lab 5 just before police arrived.

At a press conference later yesterday afternoon Paul E. Gray, associate provost of M. I. T., explained that it was the City of Cambridge and not M. I. T. which sent the police into action when the pickets were deemed to be unlawfully assembled.

Although M. I. T. owns the I-Labs they are not on its property and it is uncertain whether or not the court injunction obtained against the NAC Monday is applicable to the labs.

With the police drawn in formation just 40 feet away from the pickets M. I. T. faculty members-including Stephen L. Chorover, associate professor of Psychology, and Jerome Lettvin, professor of Biology and Electrical Engineering-made a futile effort to convince the demonstrators to disband.

"You've won the victory, you've closed the labs, there's no need for more blood, for God's sake, "Lettvin said, tears rolling down his cheeks. But the protestors continued chanting "MIRV goes first" while he spoke. "My God, they won't listen." Lettvin said.

Just before police started moving down Osborn St.-marching and chanting in cadence-someone inside the building turned a firehouse on demonstrators outside the main door.

Police carried both rifles with telescopic sights and tear-gas shotguns near the back of their formations, and all carried gas masks around their waists. The Cambridge police and the Boston Tactical Squad handled most of the actual dispersal, pushing demonstrators back up Osborn St. to State St. and then onto Mass Ave.

Cambridge police, wearing black helmets and carrying their nightsticks in both hands across their chests, kept in formation and did not charge the crowd. But some members of the Boston Tactical Squad, wearing baby-blue helmets, appeared to go out of control at the rear of the line and randomly clubbed retreating demonstrators.

At one point an unidentified officer broke ranks and attacked a picketer until he was forcibly restrained by his sergeant.

The 170 state police present, in bright orange raincoats, were not deployed until the end of the action.

Gray explained at the press conference that police were ordered to march with their clubs held fast across their chests and not to swing them needlessly.