(Reuters) - Three teenagers were arrested in Arizona after police say they were launching rocks at cars and pedestrians with a slingshot in an apparent "copycat" attack inspired by a wave of vehicle shootings along a major highway in Phoenix, authorities said Sunday.
Maricopa County Sheriff Joe Arpaio said at a news conference that the 18-year-olds admitted to shooting the slingshot at several cars and pedestrians between 3 p.m. and 7 p.m. on Saturday.
Authorities do not believe the three are responsible for firing bullets and other projectiles at 11 vehicles in the past two weeks along a 10-mile (16-km) stretch of Interstate 10 where it runs through the Phoenix metro area.
"This probably is a copycat but that's still serious and I'm sure there will be copycats out there," Arpaio said.
The teens remained in jail on Sunday on charges of criminal damage and conspiracy, said Colonel Frank Milstead, director of the Arizona Department of Public Safety.
The three were using a slingshot and granite rocks to smash windows out of cars traveling on the east side of Phoenix, near the suburb of Mesa, Milstead said.
They attacked six pedestrians and seven vehicles, Arpaio said. They were caught when the victims in one of the vehicles were able to report their license plate, he said.
The spate of vehicle shootings since Aug. 29 has left the community on edge. Gunfire was involved in eight incidents under investigation.
A 13-year-old girl who suffered a slight cut to her ear has been the only injury reported.
Milstead said there has not been a confirmed highway shooting in that area since Thursday but motorists should stay alert.
"Don't kid yourself. What the kids were doing last night was absolutely lethal," he said. "None of us should have to drive the highways and roadways and worry about people just randomly shooting items at our vehicles."
On Saturday, police said a 19-year-old man who had been detained for questioning was not their prime suspect.
Milstead has described the incidents on the interstate, the southernmost transcontinental highway in the United States, as "domestic terrorism."
On Sunday, he said police would be on high alert after the Arizona Cardinals football game just blocks from the interstate.
"We have an incredibly large footprint along the I-10 corridor," he said.
(Reporting by Karen Brooks in Austin, Texas, and Letitia Stein in Tampa, Fla.; Editing by Bill Trott)