Toronto police are searching for a man who sprayed an unknown substance on a TTC bus in the Jane and Finch neighbourhood Tuesday morning.

Officers responded to the incident just after 8 a.m. near Jane Street and Eddystone Avenue where a man sprayed an unknown substance on the bus.  The substance left the driver and some passengers experiencing difficulty breathing, said Const. Jenifferjit Sidhu.

One passenger was sprayed in the face, and another passenger reported feeling a burning sensation, Sidhu said.

The man left the bus, and when police arrived they began searching for him.

Paramedics treated people at the scene, police said.