All the three seriously injured are "out of danger".
"The victims were going for a marriage in Mayapuri area in west Delhi when the collision took place at around 2 AM. The bus overturned in which 19 were injured," police said.
The grievously injured have been admitted to AIIMS and Sir Ganga Ram Hospital while those sustaining minor injuries are undergoing treatment at other hospitals, they said.
"Laxmi 45 yrs, Upasna 34yrs & Sajid 30 yrs sufferd injuries in bus-trk collisn. Both ladies admtd in AIIMS Trauma & Sajid@Gangrm hspt. All out of dangr (sic)," DCP (South West) Surender Kumar tweeted.
Delhi Cantonment is a high-security zone where vehicular speed limitation is a norm.