The pitter-patter of little feet caused a lot of trouble yesterday for Shadyside businesses. Squirrels on a power line knocked out power and phone service for four hours to many shops and restaurants.

"We've lost a lot of business today," said Susie O'Leary, manager of Prantl's Bakery, which stayed open despite the lack of lights, heat, refrigeration and its cash register.

An unrelated power outage affected shops in Monroeville Mall for about 20 minutes, starting at 2:45 p.m.

The Shadyside outage started around 1:30 p.m. when "a couple of frisky squirrels" on power lines shorted out a transformer on Culloden Way, near Walnut Street, said Duquesne Light spokesman Joe Balaban.

The short caused a surge of power called a "fault current" to shoot through the power lines. That surge hit a weak spot in the power lines at South Aiken Avenue and Walnut, which sent the lines falling toward the street and cut off power to 2,800 customers.

The power lines hit at least one car. A female passenger in one car was "made anxious by the whole thing" and taken to the hospital, said Mr. Balaban, noting that she was not seriously injured.

Within an hour, Duquesne Light restored power to all but 160 customers, said Mr. Balaban. But the number without power included many stores and restaurants along Walnut, Aiken and nearby side streets.

Some, like J. Crew, Ann Taylor and Victoria's Secret, closed for the day. Others toughed it out.

Just before 5 p.m., employees at the William Penn Tavern on Bellefonte Street were unwrapping flashlights that they had just purchased from Rite Aid across the street, which had power.

The bar had closed its kitchen and was only serving draft beer. Employees shivered in sweat shirts from the lack of heat, but a few customers drank on despite the conditions.

"We feel colder than the beer is," joked one woman sitting at the bar.

The power returned at about 5:15, just as darkness was setting in.

Still, the businesses fared better than the squirrels, whose bodies lay along Culloden Way before they were collected and photographed by Duquesne Light employees.