(Photo courtesy of Arizona Department of Public Safety)

Troopers and detectives on scene conducting an investigation into projectile hitting semitruck in Phoenix on Sept. 10, 2015.

(Photo by Sky Schaudt - KJZZ)

A Phoenix freeway sign asks drivers to report suspicious activity on Sept. 9, 2015.

The search for a suspect in a string of Phoenix freeway shootings took on frenzied pace Thursday as police jumped from one spot to another, investigating five more reports of vehicles being shot as a panicked public flooded a hotline with tips.

Police confirmed one of these reports, raising to 11 the number of vehicles struck on Phoenix-area freeways since Aug. 29. Eight were hit by bullets and three by "projectiles" such as BBs and pellets.

One girl's face was cut by glass as a bullet shattered her window.

The Paradise Valley Unified School District, which encompasses schools in Phoenix and nearby Scottsdale, informed parents Thursday afternoon that school buses would be avoiding the area of State Route 51 and Shea Boulevard in north Phoenix as a precaution.

The Arizona Department of Public Safety was investigating whether a vehicle in that area sustained damage from a bullet or some sort of projectile. Phoenix police said there is no immediate threat to schools in the area.

Authorities are appealing for help through social media, news conferences, TV interviews and freeway billboards. The messages have morphed from "report suspicious activity" to "shooting tips" to the more ominous "I-10 shooter tip line" on Thursday.

DPS spokesman Raul Garcia said they’ve received hundreds of tips to the hotline and encourages them to keep coming.

"Somebody knows something about this. Somebody knows this suspect or suspects. And we’re asking that individual or those individuals not to sit around and wait for this to turn into a fatality," Garcia said.

As the search continues, there are now reports of vigilantism. Garcia said no one should take matters into their own hands.

“It adds to confusion. When we’re tying up resources to respond to armed individuals, law enforcement has to check each one of those incidents out,” said Garcia .

Incidents Being Investigated By Arizona DPS

On Thursday alone, drivers reported possible shootings of an armored truck, two cars and two tractor-trailers. Authorities and TV crews scrambled to these scenes, only to discover minor damage.

Only one of these proved to be a shooting, Garcia said. A commercial truck driver found a bullet hole in his cargo area after making hours of deliveries, so it was impossible to know where or exactly when it happened.

As the shootings intensify and get more attention, many drivers are taking alternate routes.

Ron Freeman, who works at a truck stop near Interstate 10, said he called his wife and family and told them to stay off the freeway until the situation calms down.

"It's kind of spooky, man, when people can't drive up and down the interstate unless they're getting shot at, but this is pretty dang scary," Freeman said.

The shootings haven't fit any obvious pattern. Most happened on Interstate 10, a main route through Phoenix. Bullets have been fired at various times of the day, striking a seemingly random assortment of vehicles, from an empty bus to tractor-trailers to pickup trucks, cars and SUVs.

Helicopters flew up and down Interstate 10 on Thursday as an officer monitored a wall of TV monitors carrying live surveillance video from every freeway in metro Phoenix. The Arizona Department of Public Safety has enlisted the help of the FBI, Bureau of Alcohol, Tobacco and Firearms, local police and undercover law enforcement officers.

"We have a number of officers ... both uniformed, non-uniformed, plainclothes, undercover vehicles, marked vehicles on the road patrolling, looking for the suspect, looking for leads," said Bart Graves, another DPS spokesman.

DPS Director Frank Milstead has referred to the incidents as "domestic terrorism crimes" without providing any information about specific terrorist groups that might be involved. He said the characterization means that "anytime that you have multiple shootings against American citizens on a highway, that's terrorism."

Many longtime Phoenix residents still remember the random shootings that terrorized the public a decade ago. Nearly 30 people were shot, and eight killed, including a cyclist who was riding down the street and a man who was sleeping at a bus stop. Two men were eventually caught and convicted.

Anyone with information should call DPS at 602-644-5805.

Updated 9/10/2015 at 8:33 p.m.