HOUSTON (AP) An 11-year-old Houston-area girl lost one leg and seriously injured the other when she was run over by a train.

Gisselle Marroquin, 11, was playing with some friends on tracks behind their homes in a neighborhood east of Houston late Friday afternoon when a Union Pacific freight train ran over her legs, authorities said.

Lt. John Legg with the Harris County Sheriff's Department said a group of five children would stand on the tracks, wait for trains to pass, then grab the side of the train and drag their feet behind them. Legg said the girl slipped and was caught under the train.

She was taken by helicopter to the Texas Medical Center.

Alex Rodriguez, a spokeswoman for Memorial Hermann-Texas Medical Center, said Saturday the girl was in critical condition. Rodriguez said she was authorized only to provide a condition report and could not say if surgeons were attempting to reattach the severed left leg.

Neighbors used a belt and extension cord as tourniquets until paramedics arrived.

Union Pacific spokeswoman Raquel Espinoza-Williams told the Houston Chronicle the two-man crew in the train locomotive never saw the girl and wasn't aware of the accident until sheriff's deputies contacted the railroad. The 52-car train then was stopped in the Highlands in East Harris County about 10 minutes later.

The railroad is conducting an investigation. The speed limit on the track in the area where the accident occurred is 10 mph.

"This is devastating for our crew," Espinoza-Williams said. "They have families and children. This affects them deeply."

Officials said the girl and some of her friends had successfully ridden a train earlier but on their second attempt she slipped.

Copyright 2009 The Associated Press.