LOS ANGELES, AUG. 12 -- Sheriff's deputies drew their guns on a mother and her three children after her teen-age son pointed a toy pistol at a plainclothes detective on a southern California freeway, authorities said today.

The incident, the second involving a toy gun in as many days, was one of the latest episodes in a rash of violence that has turned the region's highways into a terror zone.

Today shots were fired at a man driving along the freeway and a day earlier, gunfire shattered the window of a car carrying three women to lunch. There were no injuries in either shooting.

Acting Police Chief Robert Vernon told a City Council hearing today that the number of freeway shootings has nearly doubled in the first half of this year, compared with the same period last year, rising from 15 to 26.

Vernon blamed worsening traffic conditions for the increasing violence.

"I don't think we can blame the media for this," he said. "It has been increasing gradually for the past five years."

Sheriff's detective Ralph Richards, 33, driving an unmarked car, had stopped for a red light at the bottom of an exit on the westbound Pomona Freeway late Tuesday night when he saw the teen-ager lean from the car and point what the officer thought was a .45-caliber pistol, Sheriff's Deputy Van Mosley said.

Richards sped through the red light into a parking lot and called for assistance from uniformed deputies, Mosley said.

Deputies stopped the car a few blocks away and ordered the driver, Rosie Kano, her two sons, 16 and 10, and a daughter, 11, out at gunpoint, Mosley said.

"It could have been a very tragic situation if someone had misunderstood directions," Mosley said.

Deputies released the family and returned the gun, a realistic replica of a .45-caliber pistol, after talking to Kano. A toy replica of an Uzi submachine gun was also found in the car.

Kano admitted that her 16-year-old son had leaned from the window of the car and "pointed the toy gun at the detective," he said. She apologized and explained to deputies "that she has had problems controlling her son," he said.