A wreck in Charles County that killed a 17-year-old and her 7-month-old son and left a 15-year-old in critical condition started as a road rage incident, police said yesterday.

Maryland State Police said the incident started about 6:30 p.m. Tuesday when Rachel Susan Townsend, 17, was cut off by another driver on southbound Route 301, just outside La Plata.

Townsend made a furious hand gesture and started cursing when the Mitsubishi Galant cut her off, according to Lt. Randy Stephens.

Townsend speeded up to try to catch the other car, but a third car not previously involved -- a Toyota Corolla -- positioned itself to block Townsend's car from catching the Mitsubishi, police said. Stephens said the Corolla driver tried to act as a "buffer."

As Townsend accelerated, she ran into what police described as a "wall of water" and lost control of her car in the heavy rain.

Her car ran off the right side of the road, entered a ditch, struck several trees and overturned, according to the state police report.

Townsend was thrown from the car and pronounced dead at the scene. Thomas Damien Townsend, her 7-month-old son who was riding in his child safety seat in the back seat, was also killed.

Two other passengers in Townsend's car were injured. Alexis Dawn Washington, 15, was listed in critical condition at Prince George's Hospital Center late yesterday. The injuries of Kilarissa Rochelle Washington, 14, were not life-threatening, police said.

Relatives of Townsend and the Washingtons could not be reached.

The three drivers involved were 17 to 24, investigators said.

Stephens said that the investigation is continuing.

Staff researcher Bobbye Pratt contributed to this report.