A Grade 7 student Keziah Edwards-Young has been identified as one of two children killed in a horrific head-on crash late Sunday night in Mississauga, Peel District School Board says.

A 40-year-old man driving alone in a Mazda 6 was also killed in the collision.

The flag at Erin Mills Middle School was lowered to half-mast in the 13-year-old boy's honour on Monday, said principal Monika Hurford in a letter sent home with students. The flag will remain as such until after Edwards-Young's funeral.

"This tragedy has brought great sadness to the students and staff at Erin Mills," Hurford said. "Keziah was a well liked student — a valuable member of our school community. We will miss him."

Counsellors will be available at the school for students and staff as long as they are needed, the letter added.

"A lot of them are very distraught," Peel Regional School Board spokesperson Carla Pereira told CP24 on Monday afternoon. "Keziah had a very large circle of very close friends.

"The news is devastating for that school community."

A memorial table has also been set up in the school's library where students and staff can share messages of condolences, Pereira added.

A five-year-old child was one of the three lives claimed by the two-vehicle crash.

Three other people, including a woman and a girl were injured in the accident that happened on Winston Churchill Boulevard, near Queen Elizabeth Way, just before 11 p.m.

The man who died was driving the Mazda when he lost control of his vehicle for unknown reasons, swerved into the oncoming lane and collided head-on with a northbound Mercedes Benz, Peel Regional Police Const. Rachel Gibbs said.

He was pronounced dead at the scene.

Five people were in the Mercedes when it was hit. A woman, 25, who was a passenger in the car is in hospital with critical injuries. Another passenger, a seven-year-old girl is also in hospital in stable condition. The boys — aged five and 13 — were rushed to hospital where they later died of their injuries. The driver, a 24-year-old man suffered minor injuries.

Gibbs said investigators have not yet determined whether the people in the Mercedes are related to each other.

Police are speaking to eyewitnesses but are reaching out to anyone else who may have seen the crash or the vehicles beforehand, or was using a dashboard camera, Const. Bancroft Wright said.

Investigators with Peel's Major Collision Bureau still haven't determined why the driver of the Mazda swerved into oncoming traffic or if impaired driving was a factor.

"It would be a Sunday night pretty close to a fairly popular complex for entertainment. I anticipate we will have witnesses," Wright said. "We hope if anyone did see anything, they will contact police or Crime Stoppers."

Winston Churchill Boulevard remained closed in all directions at the QEW overnight because of the fatal crash but all lanes reopened by 6:30 a.m.