A morning snow squall was blamed for a rash of accidents across the district yesterday, including a crash on Interstate 79 in Robinson that killed a 13-month-old boy.

State police reported that Judah Scrutchins was in a northbound sport utility vehicle that crossed the grass median and struck a southbound tractor-trailer head on near the Crafton exit around 9:22 a.m. The boy died at the scene. His female twin Julia and 4-year-old brother Jaxon were taken to Children's Hospital. All were in child safety seats.

The driver, Tracy Gebhardt, 34, of New Brighton, mother of the children, was taken to UPMC Presbyterian. Her front-seat passenger, Laura Kay Federoff, 34, of Lake City, Erie County, was taken to Allegheny General Hospital and was in critical condition. The conditions of Ms. Gebhardt and the surviving children were not available.

The tractor-trailer driver was not injured.

The accident was one of many reported throughout the day. The wind-whipped snow started around 9 a.m., and soon after, emergency dispatchers began receiving numerous calls about crashes.

Outbound traffic on the Parkway West was stopped for nearly two hours due to multiple crashes in the Carnegie area. State police alone reported responding to 18 incidents in Allegheny County.

Pittsburgh police Lt. Michael Piasecki said officers on the North Side responded to five accidents, "which is about five more than usual."

Pittsburgh City Councilman William Peduto said he encountered three wrecks on his drive on Fifth Avenue toward Downtown.

"I was in one," he said. A car pulled in front of him at Fifth and Denniston Avenue, he said, and he slid into it. No one was hurt, and his Mini Cooper was undamaged.

On Monday night, the National Weather Service predicted the snow would begin around 11 a.m. But a revised forecast yesterday at 7 a.m. put the snowfall at between 8 and 10.

City and county agencies said they were prepared and that the change in forecast did not affect their response.

"We had some heavy squalls throughout the area [and] we had some lingering rush hour traffic that hit those areas and we had some crashes," said Pennsylvania Department of Transportation spokesman Jim Struzzi. "Even though the [salt] truck might have gone through there five minutes before then, the way it's coming down, it's going to impact traffic."

Joe Olzcak, deputy maintenance director for Allegheny County, said the county had about 32 salt trucks out at 4 a.m.

Pittsburgh Public Works Director Guy Costa said the city had 50 salt trucks loaded and ready to go, and deployed them as soon as the snow started. "The bad thing is, it came down fast," he said. Wind blew snow back on the roads after they were cleared."

Port Authority spokesman Dave Whipkey said buses were involved in a couple of minor accidents between 10 and 10:45 a.m. No injuries were reported.

State police said weather probably factored into a fatal crash on U.S. Route 62 in Mercer County yesterday.

Christian M. Stella, 31, of Hermitage, died when her northbound SUV spun and collided with a truck driven by John E. Fox, 51, of Mercer, near Old Sharon Road in Lackawannock Township at 2:41 p.m. Police did not know the extent of Mr. Fox's injuries.