They were admitted to the burns unit of the Dhaka Medical College and Hospital on Saturday night. Condition of two of them was critical, doctors said.
The incident occurred around 9:30pm near Dhaka Udyan at Mohammadpur embankment soon after unknown miscreants had hurled petrol and handmade bombs at a police bus near Matsya Bhaban.
Mohammadpur Police Station OC Azizul Haque said miscreants fled after setting the bus blaze, which was coming from Savar.
Of the victims, five are from two families.
The injured have been identified as Abu Taher, 75, his sons 'Sujon', 22, and Abu Bakkar, 20, Nurjahan Begum, 35, her daughter 'Ritu', 14, 'Billal', 25, 'Arman', 35, 'Monowara', 30, and two-year old 'Rifat'.
Doctor on duty at the burns unit, Partho Shankar Pal, told reporters that conditions of Taher and Billal were critical as their windpipes were damaged.
During these 12 days of the nationwide nonstop transport blockade which began on Jan 5, arson attacks across Bangladesh have burned at least 20 people to death.
On Saturday morning, a bus was set on fire at Rayerbagh that also left at least five people, including a female student of Jagannath University, burned.
Four more buses were also torched in capital Dhaka throughout Saturday.
Around 7pm, a bus was set alight at Dhanmondi while two others were set afire at Mirpur's technical college intersection in the afternoon and evening, respectively.
Earlier, a minibus was torched at Mirpur-13 around 7:30am.
An auto-rickshaw used for the transportation of bdnews24.com employees was set on fire around 8:30pm at Moghbazar.
However, it was not carrying anyone at that time.