Across the nation, police departments are cautioning high school students about participating in local “senior assassin” games, which have led to severe injuries and even arrests.

This game is typically enjoyed by graduating high school seniors, where they aim to track down and eliminate their peers from the game by using squirt guns or other playful weapons.

“Each player is given a target, and you need to ‘eliminate’ them using a water gun while trying to avoid being targeted yourself,” explained Carter Lennie, a student from Glen Ellyn, Illinois, speaking to Nexstar’s WGN about the game’s rules.

Those who take the game too far, however, can end up injuring themselves or their friends, officials say.

Isaac Leal, a 17-year-old high school student in Texas, suffered a serious injury just last month after reportedly hanging from the back of another student’s Jeep while playing the game, police in Arlington confirmed to Nexstar. Leal’s mother told Dallas’ KXAS the driver reversed her vehicle and drove away with Leal still on the back.

“She hit a dip and that’s where I was told, allegedly, he flew off the Jeep and hit his head,” Raquel Vasquez, Leal’s mother, told the outlet.

Leal was still fighting for his life this week, KXAS reported.

Carrying a toy weapon — even one that may appear to be an obvious toy up close — can also cause concern among residents who live in the communities where these games are played. Police departments across the country have reported an influx of calls from concerned citizens reporting armed strangers on their property. Law enforcement officials in Utah said last month that some of these citizens had armed themselves after seeing an unknown, seemingly gun-toting figure wandering near their home. (Students have been known to play both on-campus and off.)

In February, one teenager in Florida was even shot by an off-duty cop while holding a water pistol in a Nassau County homeowner’s yard, NewsNation reported. The teen is expected to recover, police said.

There have also been reports of students equipping themselves with not just water guns, but with toy guns designed to fire gel- or water-based pellets.

“While these gel projectiles may seem harmless, they can cause serious injury,” a sergeant with the Fort Lupton Police Department in Colorado said this month, per Nexstar’s KDVR. “Even more troubling is that I personally witnessed high school students today hanging out of moving car windows and shooting other students on public roadways.”

Participants can also get themselves into legal trouble, depending how — and where — they play.  Another student in Utah is facing a terrorism charge after allegedly charging into a hospital with a Nerf gun while chasing a classmate, Nexstar’s KTVX reported earlier this month. Police said the incident nearly prompted a lockdown of the facility, according to the station.

To minimize risks of injury or arrest, police in jurisdictions across the country have issued warnings or guidance for participants, telling them to use only brightly colored toy weapons, and to stay away from school grounds and private property.

Police are also urging participants to carefully consider their actions and behavior while playing the game, and decide if the game’s reward — which may be cash, a prize, or just bragging rights — are worth putting themselves in physical danger or legal trouble.

“We hope that parents can speak with their kids about the dangers of this game and the possible consequences,” one police department in Massachusetts advised, after a student was recently seen waving a toy gun from a moving car.

“While we understand this game is for fun, we want to remind the public that this game must be played responsibly and that it will result in a police response when we receive calls of this nature.”