John D. Sturgeon knew something was desperately wrong as he looked into the sky outside his Memorial Drive office building yesterday morning.

Before his eyes, a State Police helicopter, locked in a tailspin, lurched to one side and smashed onto the roof of the two-story Harvard Yacht Club building, killing the two state police officers and two American Telephone and Telegraph (AT&T) employees on board.

"It circled over, then it turned sideways and just came straight down," Sturgeon said. "It didn't explode--it was going straight down, and there was about a second, and then a big thud."

"It looked to me as if [the pilot] was trying to hit the water," Sturgeon said.

Eight members of the MIT Emergency Response Group were drinking coffee in the lobby of a building across the street when they looked out the window to catch the last few seconds of the helicopter's descent.

Utilities Construction Coordinator David M. Barber said the main rotor was motionless as the helicopter fell. His account essentially agreed with Sturgeon's: "The only thing running was its tail section...It made almost a 180-degree spin. It spun around relatively quick."

Barber said the tail of the aircraft slammed into the building first, pulling the entire craft down onto the tiny boathouse.

The MIT emergency crew's members, who are trained to rescue people from confined spaces but not from helicopter crash scenes, immediately rushed out to the sailing center.

"There was no time to get equipment," Barber said. "We just acted as best we could at the spot."

In a rush to reach the victims, the crew brokethrough a door leading to the center's preliminarycatwalk, Barber said.

The wreckage was strewn on the roof above them,and the crew had no way of climbing up.

They knocked on the center's door, but no onewas inside--the building was closed and not inuse, according to Barber.

The crew kicked down the building's door andfrantically searched inside for a way to reach theroof, he said.

They found a six-foot step ladder in thebuilding and brought it outside, Barber said.

But the ladder was too short, so four crewmembers including the emergency medical techniciancrawled the remaining distance on other crewmembers' hands and shoulders.

"We did everything we could to get up there,"Barber said. "Time was of the essence."

The impact hurled fragments of the helicopterover the roof and onto the ground.

"There were two big pieces and a couple hundredpieces on the ground," said Steven M. Turner ofRoxbury, who witnessed the crash as he sat in abus on the Mass. Ave. Bridge. "[It was] just onebig mess."

"It was so mangled it no longer looked like ahelicopter," said Michelle A. Kamin, anoffice-worker who watched the rescue team from heroffice on the other side of the street.

Gasoline from the twisted helicopter wreckagewas gushing onto the roof and into the river,bringing with it the danger of a massiveexplosion, witnesses said.

"When we realized how much gasoline was beingspilt on roof, we didn't want any more [people] on[the roof] than necessary," Barber said. The otherrescue workers stayed on the ground to keep thegrowing crowd away from a possible explosion.

Officials from the state's EnvironmentalProtection Agency worked to contain the spill asfire-fighters sprayed flame-retardant foam intothe building.

Above them, the four team members raced to pullthe helicopter's crew out of the wreckage butfound no vital signs on any of the four victims,Barber said.

"They looked like clumps, they didn't look likebodies," Kamin said.

Other MIT emergency medical technicians hadarrived while the crew was getting on the roof.

State police and Cambridge police and firedepartment personnel followed quickly.

"They got there almost immediately," Kaminsaid.

Barber said that quick work by the emergencyresponse personnel kept the scene from becomingchaotic.

"It was congested...[but] organization fellinto place relatively quickly," Barber said.

Ironically, when they witnessed the crash,Barber's team had been taking a break frompracticing emergency procedures in a nearbybuilding.

"We were talking, ready to finish and get backto our job," Barber said. "Ten minutes either waywe wouldn't have been there."

Marios V. Broustas contributed to thereporting of this story.