Two 15-year-old boys are facing more than 36 charges after a pepper spray incident on an OC Transpo Route 87 bus at the South Keys Transitway station on Sunday.

The Ottawa fire department's hazardous materials team, paramedics, police and OC Transpo security staff responded at about 2:45 p.m. Sunday to the Transitway station on Bank Street.

A girl had called 911 to say she was having difficulty breathing after a substance was sprayed on the bus, police said.

A witness told the CBC’s Judy Trinh there was an altercation on the bus and that one teen sprayed others with pepper spray. About 20 people had just boarded the bus before the incident occurred, the witness said.

The hazardous materials team found that the substance was a dog repellent spray, police said.

Paramedics assessed two people at the scene who refused treatment. Another two people with minor injuries were taken to the Children's Hospital of Eastern Ontario, paramedics said.

The southbound lanes of the Transitway were shut down for an hour.

Two 15-year-old boys are facing 18 charges each, including:

5 counts of assault with a weapon.

5 counts of depositing a volatile substance.

5 counts of administering a noxious thing.

1 count of mischief under $5,000.

1 count of common nuisance.

1 count of possession of a dangerous weapon.

The boys were set to appear in court on Monday. They cannot be identified due to the provisions of the Youth Criminal Justice Act.