LAS VEGAS (AP) _ An attacker killed a 3-year-old girl and repeatedly stabbed her 10-year-old sister with a butcher knife early Wednesday outside a Mesquite casino where their mother was gambling, authorities said. The suspect was arrested in Utah.

The girls' mother and her boyfriend had been confronted inside the casino by a man who demanded they pay him $125, said Lt. Jerry Hafen, a Nevada Department of Public Safety spokesman. Authorities believe the money had been stolen from the man to repay a debt to the couple.

The mother and her boyfriend were still inside the casino when the girls were attacked shortly before 2 a.m. inside the family's trailer at a casino RV park, Hafen said.

``The 10-year-old said a man knocked on the door and told them that their mommy had been hurt,'' Deputy Police Chief Joe Szalay said. ``When she opened the door, he held his hand over her mouth and started to stab her.''

Police said the girls, their mother and her boyfriend were living at the CasaBlanca casino recreational vehicle resort in Mesquite, a fast-growing town about 80 miles northeast of Las Vegas near the Utah state line.

The 10-year-old girl was in critical condition Wednesday afternoon, said Rick Plummer, spokesman for University Medical Center in Las Vegas. She was expected to survive, Hafen said. Authorities have declined to release the sisters' names.

Police said Beau Santino Maestas, 19, and two teenage girls surrendered without incident after Utah troopers stopped their car on Interstate 15 before 8 a.m. in response to a Mesquite police bulletin.

Maestas will be returned immediately to Nevada and charged with murder and attempted murder, Hafen said. He declined to say if the teenage girls, 16 and 17, would be charged.

Utah Highway Patrol spokesman Doug McCleve identified the other occupants of the car as Maestas' girlfriend and his younger sister.