When Cambridge school bus driver Joseph Colarusso slumped over the wheel on an early morning run two weeks ago, the three junior high school safety patrols who ride his bus--Cheryl Doty, Susan Landry and Robin Messer--didn't know what to think.

Colarusso was having a heart attack, and the Cambridge City Council Monday night unanimously approved a commendation to the three girls for their quick action in getting him medical assistance.

"He said he had chest pains," Messer said yesterday, "but Cheryl asked him if he was serious, because it was April Fools' Day."

While Doty and Messer waited on the bus with Collarusso and 13 children, Landry ran to a construction site across the street from the bus stop and returned with a Cambridge policeman.

The officer helped Colarusso from the bus and the three girls opened the emergency door to let out the children--ranging in age from five to nine years old.

After the bus was empty the girls helped hold the driver's head while the officer administered first aid and raided for an ambulance.

After Colarusso was taken to Mt. Auburn Hospital, Doty and Landry went to the other bus stops and brought all the children who ride the bus to Fitzgerald Elementary back to Gold star Road to wait for another bus.

An announcement had been made at Fitzgerald before the three girls arrived, "and all the kids were asking us questions about what happened," the 12-year-old Messer said.

A copy of the City Council's resolution, which commends the girls for "their quick and decisive action," will be placed in each girl's school file. "That's okay with me," Messer said.