Police are looking for three teens who they say are “persons of interest” in the discovery of a suspicious package outside an Etobicoke elementary school.

At around 5 p.m. Sunday, witnesses reported seeing three boys playing with a dark item behind St. Eugene Catholic School on Westroyal Road.

Toronto police’s Chemical, Biological, Radiological and Nuclear squad (CBRN) were called in to investigate the item, which was described as being about the size of a soccer ball and made of black electrical tape.

The sphere had a fuse poking out of its side and had similar characteristics to an “ACME cartoon” bomb, Toronto Police Sgt. Al Hobbins said Sunday.

Donning protective gear, the CBRN made two unsuccessful attempts to detonate the package within the school’s playground.

The package was successfully blown open at around 9 p.m. after a robot was brought in to assist in the detonation.

The blast sparked an intense flash and burned brightly for several seconds before fading.

Investigators believe the unusual package was made up of fireworks but said crews sent the contents away for further analysis.

Speaking to CP24 via phone Monday morning, Toronto Catholic District School Board spokesperson John Yan said the suspects do not appear to be students at St. Eugene.

“It was a random act,” he said. “It looks like a prank gone awry by three young individuals.”

Police describe the so-called “persons of interest” as three white males who are approximately 14 years old. They were last seen wearing backpacks.

If apprehended, police say the suspects could face mischief charges.

Yan said the school remains open today and that counsellors will be available for those who feel uneasy about what happened.

Security guards were also called in Sunday to watch the school grounds overnight.

“As you know, in this age of social media and 24-hour news, students will have seen the coverage and may be disturbed by it,” Yan said.

“We are assisting with the investigation. We will be handing over any external footage that we might have around the school and we’ll take our direction from the Toronto Police Service.”

Anyone with new information about the investigation is being asked to call police or Crime Stoppers.