Toronto police are investigating after a person allegedly sprayed an unknown substance on a TTC bus.

Emergency crews were called to the scene on Jane Street and Eddystone Avenue, near Finch, just after 8 a.m. on Tuesday.

Police said passengers on the bus complained about breathing problems and one person is complaining about a burning sensation in their chest.

Authorities are searching for the suspect.

No further details have been confirmed at this time.

This comes a few days after a man allegedly approached two passengers on the Spadina subway line and sprayed them with an unknown substance.

One of the victims was taken to an area hospital suffering from redness and irritation to the eyes.

That suspect is still at large. Police say he is considered violent and dangerous.

He is described as being six-feet tall, wearing a black leather jacket, grey hoodie, black pants, dark shoes with white laces. He was carrying a small spray bottle.