A speeding car hit a utility pole Friday night and careened into a group of five girls on a sidewalk as they walked to an overnight birthday party, killing all of them, authorities said.

The driver of the 1975 Cadillac, Scott Karcz, 17, and his sister, Tina, 10, were taken to two Green Bay hospitals, police said. Scott was in critical condition at St. Vincent Hospital, a spokeswoman said. A nursing supervisor at St. Mary's Hospital declined to release information on Tina."The car must have been going at a fairly good rate of speed," Lt. George Weitzel of the Brown County sheriff's department said. "They must have lost control. It hit a (telephone) pole and then a bunch of girls. It then hit a tree." Weitzel said there were no witnesses.

"It was married to the tree," he said of the Cadillac.

Weitzel said he believed the speed limit on the street was 25 mph.

Four of the girls were pronounced dead at the scene and a fifth died at St. Mary's Hospital, Weitzel said. The five girls were all students at Glenbrook Elementary School, according to Pulaski High School Principal Guy David. He said the driver of the car was a student at the high school.

The children were walking near the village post office and police station when they were struck, David said.

Authorities said an accident reconstruction team was working at the scene.

"This is going to be a real problem for the community to deal with. It will be very difficult," David said. "In a small community like this, everybody knows everybody."