On Sunday, police received a 911 call from a frightened resident after she saw a man wearing a white shirt run into her garage, holding what she believed to be a “black gun,” according to a letter sent to parents by Officer Philip Powers, Hopkinton’s school resource officer.

The student, police said, was playing “Senior Assassin,” a game in which members of the senior class go after an assigned target — other students — to soak with a water gun. The game is played in many communities as students prepare for graduation.

A tradition among high school seniors got out of hand in Hopkinton last weekend after a student was mistaken for a gun-wielding criminal, creeping around inside a resident’s garage.


In the letter, which was forwarded to the Globe, Powers said the resident closed the garage door, trapping the person inside.

Around that time, police received a second 911 call from a person who said a car parked nearby was screeching its tires, possibly attempting to flee the scene.

Powers said the person locked in the garage located a garage door opener inside the resident’s vehicle and escaped. The person was then picked up by the car that was seen leaving the area.

Police were dispatched to the area and pulled over the vehicle, Powers said, “withdrawing their service weapons at a low ready position.”

But the operator and two other people in the car were immediately identified as high school students, Powers said.

“The officers at this point realized that this was probably students at the high school playing senior assassin,” he wrote in the letter. “A large Super Soaker water gun was found in the vehicle.”

Powers said police went back to the resident’s house to explain the situation to the homeowner, a 70-year-old woman who lives alone. No high school students lived at the targeted address.


Powers said the woman decided not to press charges. The students could have faced felony charges including armed home invasion, assault with a dangerous weapon, and breaking and entering, he said.

“This game is not sanctioned by Hopkinton High School or the Hopkinton Police Dept.,” Powers told parents. “We ask that you please talk to your children about this potentially dangerous game before something worse happens.”

Police in other cities and towns have also warned residents about students participating in the annual “Senior Assassin” game.

On April 25, Sharon Police posted a notice on Facebook, in all capital letters, that said while the department and school department don’t condone the event, it’s not illegal to play.

“They are asked to use their best judgement and to keep things safe,” police said. “If you see what you believe is a high school aged student lurking around a certain area with a water gun, most likely they will be part of the game.”

And on April 24, Bridgewater Police received a report about “two suspicious males with squirts guns,” according to a tweet on the department’s Twitter account. Police said it was “parties participating in ‘Senior Assassination’ game.”

Hopkinton Police Chief Edward Lee said the situation in his community could have put the students, who had arrived at the wrong home as part of the senior tradition, in serious danger.

Lee said any time police conduct a “felony car stop” it’s standard for responding officers to have their weapons at the ready.


He said the officers’ weapons were not pointed at the juveniles, and were kept low, “so you could react quickly if there was a threat.”

Lee, who has been chief of police in Hopkinton for three years, said he had never dealt with a situation like this in the past.

“We have had incidents before where they have played pranks, but nothing that would rise to this level and cause an extremely dangerous situation,” he said.

Lee added that he was proud of his officers for showing “great restraint” under the circumstances.

They “were quickly able to realize this was part of a prank, and not a legitimate threat,” he said. “We are just glad that it turned out in the manner in which it did.”

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.