The constable, 51 year-old Suresh Namdev Avhad, has been admitted in Fortis hospital to Mulund.
The accident took place at the T Junction of the Eastern Express Highway in Vikroli (east), at around 12.30 pm. Avhad was on his way home.
A truck hit his bike and sped away without informing the police or helping him with medical treatment.
On duty traffic police constable Govardhan Kashinath Bhoye admitted Avhad to a hospital. The Vikroli police has registered an FIR against the unknown truck driver.