Police bomb squad officers took three attempts to detonate a suspicious package after it was found on the grounds of an elementary school in Etobicoke on Sunday evening.

Officers say they were called to St. Eugene Catholic School, on Westroyal Road near Royal York Road and The Westway after 5 p.m. for a report of a suspicious package.

The Chemical, Biological, Radiological and Nuclear squad was called in to investigate.

Sgt. Al Hobbins told CP24 officers were called after a complainant spotted three boys about 14 years of age playing with a dark item behind the school.

He said the item was a sphere the size of a soccer ball, made of black electrical tape, with a fuse poking out of its side.

He said it has similar appearance to a classic "ACME cartoon" black bomb, but its contents are not yet known.

Sofia Astrella was doing her homework in a home near the school when emergency crews started to roll in.

“The response was overwhelming,” she said, as officers and firefighters converged near what she described as a “small black package” near a basketball net on school grounds.

“It didn’t seem big enough to contain anything real,” Astrella said.

She witnessed an officer crouch down and detonate the package at about 7:10 p.m.

“We saw this guy in a bigger black protective suit and he poked at something and then you heard something go off sort of like a pop. No smoke came out so there was nothing explosive in there.”

Officers clad in protective gear, along with a police robot were spotted at the scene. The package was detonated again after 7:30 p.m.

Hobbins said the first two attempts to detonate the package were not successful, so at about 9 p.m., a larger amount of explosive was used to blow the item open.

The husk exploded with a yellow flash and then burned intensely but slowed after a short amount of time.

Police said the substance inside the item will be sent away for analysis.

It is believed the item contained fireworks.

The three youths considered persons of interest are described as white males in their early teens, wearing backpacks.

Police say the youths involved could faces charges including mischief.

Toronto Catholic School Board spokesperson John Yan said security guards will watch the school overnight.

Staff at the school will meet tomorrow and councillors will be on standby if pupils express a need for assisstance.

He said there was no security camera in the area of the exterior of the building where the item and three suspects were first seen, but all surveillance footage will be handed over to police for review.