Police rescued the husband and eight-year-old child of an MIT professor from the Charles River's frigid waters last night after their car plunged from Soldier's Field Road into the river.

Antonino Magazzu, 45, was listed in serious condition at Massachusetts General Hospital, and his son Mark was in critical condition at Mt. Auburn Hospital. Both reside with Emily F. Magazzu, a professor at MIT's Sloan School of Management, on Spring St. in Somerville.

Police, who believe Magazzu lost control of the vehicle while driving past the Western Ave. Bridge, gave the following account:

.At about 9:30 p.m., a passing motorist saw the car, a red Pontiac Sunbird, partially submerged in the river.

.She flagged down a passing Metropolitan District Commission (MDC) police car, which alerted other police and rescue units.

.Harvard police were next on the scene, and about 10 minutes after the sighting MDC Lt. Thomas Quirk saw the boy floating face down 30 feet from shore and swam out to grab him. Other officers threw life preservers out to the pair to pull them in.

.Harvard police officer Al Terestre and Lt. Peter O'Hare performed CPR on the child at the scene, but found no pulse, Terestre said.

.Ten minutes later, a Cambridge fire and rescue team spotted and retrieved the elder Magazzu from 30 feet out and performed CPR.

The car had careened down a 20 foot embankment that separates the road from the river. However police found the ignition off and the gearshift in park.

Terestre speculated that the child fell out of the front-passenger door, which was facing the water and found open. Police also surmised that Magazzu was conscious enough to turn off the car's engine and dive in after his son.

A person could withstand about 30 minutes in the near-freezing water, Terestre estimated.